Occipito posterior position

In humans, preterm birth refers to the birth of a baby of less than 37 weeks gestational age. Premature birth, commonly used as a synonym for preterm birth, refers to the birth of a premature infant. Because it is by far the most common cause of prematurity, preterm birth is the major cause of neonatal mortality in developed countries. Premature infants are at greater risk for short and long term complications, including disabilities and impediments in growth and mental development. Significant progress has been made in the care of premature infants, but not in reducing the prevalence of preterm birth.[1] The cause for preterm birth is in many situations elusive and unknown; many factors appear to be associated with the development of preterm birth, making the reduction of preterm birth a challenging proposition. WHO defines prematurity as babies born before 37 weeks from the first day of the last menstrual period

Babies born this early are at risk because their internal organs, including the lungs, and fat to keep them warm have not fully developed. But with each advance in modern medicine, the chances of survival for the baby are increasing.

Babies born before week twenty four and weighing about 2lbs have a fifty percent (1 in 2) chance of surviving given the appropriate treatment in a neonatal intensive care unitPart of a hospital that is dedicated to the care and attention of newborn infants that are seriously ill or premature. It contains a variety of specialized equipment and is staffed by a team of nurses and neonatologists who are specially trained in the pathophysiology of the newborn.Visit our comprehensive glossary for more pregnancy terms and definitions., or NICU, but are at increased risk of mental and physical defects, such as cerebral palsy. This can be a frightening and worrying experience for many mothers, but specialists, called neonatologists, are trained to bring their experience and care to the neonatal intensive care unitPart of a hospital that is dedicated to the care and attention of newborn infants that are seriously ill or premature. It contains a variety of specialized equipment and is staffed by a team of nurses and neonatologists who are specially trained in the pathophysiology of the newborn.Visit our comprehensive glossary for more pregnancy terms and definitions.. These dedicated professionals will do everything they can to ensure that the outcome is a happy one.

By week twenty eight, the chances of survival are over ninety percent (9 in 10), and every week that the baby remains in the uterus and gains weight increases the likelihood of a successful outcome. By the time your baby weighs more than 3lbs, the chances of survival are ninety five percent.

Symptoms of premature labor

Premature labor often begins without warning, and it can be very difficult to know if it has started. Even your doctor may have trouble confirming the diagnosis. The problem is that medical centers may have different criteria for determining whether premature labor has begun, and many of the warning signs are also part of a normal and healthy pregnancy.

Premature labor may begin like normal labor, often with the rupture of the membranesRupturing of the amniotic sac releasing the amniotic fluid. It is usually one of the first signs of the onset of labor. Also called breaking of the waters.Visit our comprehensive glossary for more pregnancy terms and definitions., and a clear and watery or mucusy and bloody vaginal discharge. You may then begin to feel contractions, but they will feel more like a tightening of the uterus.

No results found. Click here for amazon.comThe contractions will be just like regular labor contractions, and you will feel your uterus hardening, with the contractions lasting between 60 and 90 seconds. A contraction will occur at least every ten minutes. But at this stage of your pregnancy, labor contractions may not be as strong as they would be at term.

Other symptoms of premature labor you should look for include a dull lower backache, that is impossible to relieve even if you change your position. This vague ache will not be the same as your regular lower back pains, instead it may be rhythmic and constant. You may also feel increased pelvic pressure, and gas pains, digestive problems and maybe diarrhea.

The most common causes of repetitive contractions or cramps at this stage in your pregnancy is dehydration, a full bladder or too much activity. Try going to the bathroom, then drinking a couple of glasses of water or juice. Rest for an hour and see if the contractions disappear.

If the signs of premature labor are still present, you should contact your doctor or midwife immediately, even if it is the middle of the night. Your doctor will encourage you to drink plenty of fluid to ensure that you are hydrated, or you may be placed on an IVThe delivery of fluid, often glucose, directly into the vein using a plastic catheter, and bag of fluid.Visit our comprehensive glossary for more pregnancy terms and definitions.. The nurses will record your weight, blood pressure and temperature and a urine sample will be analyzed to try and determine why you are cramping. A sample from the back of your vagina may be cultured for bacteria and tested for fetal fibronectin, a chemical that is produced by the fetal membranes. If you test negative for fetal fibronectin it is unlikely that you will enter labor for at least two weeks, but a positive test does not indicate an imminent delivery.

Instead, a pelvic exam will be performed and your cervix will be examined for signs of effacementA term used to describe the process during labor whereby the vagina shortens and the walls of the cervix thin as it is stretched by the fetus. At its finish, the cervix becomes one with the lower segment of the uterus. Doctors measure the extent of effacement during labor by vaginal examination and express its progress as a percentageof full effacement.Visit our comprehensive glossary for more pregnancy terms and definitions. or dilationThe opening of the cervix during labor, caused by the contractions of the uterus. The cervix dilates so that it will be large enough for the baby to pass through the birth canal during delivery.Visit our comprehensive glossary for more pregnancy terms and definitions., which would indicate the onset of uterine contractions. If there no changes to the cervix, your doctor may perform regular pelvic exams at frequent intervals or place you on an external fetal monitor to measure your contractions.

Premature labor is easier to stop the sooner it is diagnosed. Using the external fetal monitor you will be checked for contractions every five to ten minutes lasting for thirty seconds or more within an hour. Cervical dilation of more than 1 inch (2.5cm) and more than three quarters effaced are also necessary to confirm the diagnosis. Only about one third of women who think they are in premature labor have actually entered labor.

Incidence of premature labor

Premature labor occurs in about five to ten percent (1 - 2 in 20) pregnancies. The cause in over half of cases is unknown. About twenty to thirty percent (2 - 3 in 10) of cases are triggered by premature rupture of membranes, or PROM, but this is often the result of some other problem.

Risk factors for premature labor

Statistically, there are many factors that may put you at risk of premature labor, and they can be broadly categorized as general health problems, medical history problems and obstetrical complications.

Your general health will be carefully monitored throughout your pregnancy by your healthcare provider. While unusual, it is possible that your premature labor is not premature at all, but simply the result of an incorrect calculation of your due date. If you have had no prenatal care, there is an increased risk of premature labor because of poor general health.

General health problems & premature labor

poor nutrition

smoking during pregnancy

cocaine use during pregnancy

untreated maternal diseases (and complications such as anemia)

maternal infections (including syphilis and pyelonephritis)

overwork, stress and anxiety

physical trauma (such as an auto accident or bad fall resulting from domestic abuse)

teenage pregnancy

Women who have a history of premature labor are more likely to enter premature labor in a subsequent pregnancy. Your doctor will examine your medical history for factors which may increase your risk of premature labor.

Medical history problems & premature labor

two or more second trimester miscarriages or therapeutic abortions

hypertension (high blood pressure)

diabetes mellitus

thyroid problems

previous abdominal or uterine surgery (including fibroids, cyst removal but not cesarean sections)

cone biopsy of the cervix

DES daughter

Premature rupture of membranes or PROM is the most common trigger of premature labor, but other obstetrical problems may also be risk factors.

Obstetrical complications & premature labor

multiple pregnancy

congenital abnormality of the fetus or uterus

uterine structural problems (large-sized uterus, double uterus, abnormally shaped uterus or irritable uterus)

cervical problems (incompetent cervix, cervix less than 1cm long, cervix dilated more than 1cm)

retained IUD

placental problems (placental abruption, placenta previa or placenta accreta

polyhydramnios

stillbirth

Managing premature labor

If you are experiencing uterine contractions, but the cervix has not yet effaced or dilated your doctor will check to see if the membranes are intact. If they have not yet ruptured, there is a good chance that the labor can be stopped or delayed. While the decision to stop premature labor is a controversial one, it is considered beneficial for the baby and does reduce the risk of complications.

No results found. Click here for amazon.comAt first your doctor or midwife will prescribe bed rest and plenty of fluids. In many cases, simply rehydrating the body and resting on your side (the left is considered the most effective) is enough to halt the progress of premature labor. If you are in hospital, an IV may be administered to provide fluids. Bed rest and rehydration effectively stops premature labor in about half of cases.

If bed rest does not prove effective, it may be necessary to administer tocolyticA term used to describe the medical interruption and halting of contractions during premature labor.Visit our comprehensive glossary for more pregnancy terms and definitions. medications to relax the uterus and slow the contractions. Used safely since the 1970s, there are three types of drugs to arrest premature labor including magnesium sulfate, beta-adrenergics such as ritodrine (Yutopar) and terbutaline (Brethine) and sedative-narcotics. These drugs are effective in stopping premature labor in about seventy percent (7 in 10) cases.

Like all such drugs, they must be administered in a hospital or birthing center, and carry the risk of side effects including increased heart rate and palpitations, lowered blood pressure, anxiety and tremors. If successful, your doctor may prescribe continued medication orally at home.

The decision to use drugs is a difficult one, that is based on both your physical health and the stage of pregnancy. Many doctors feel that the labor should be allowed to continue without the intervention of drugs after week thirty two or week thirty four. Before administering any tocolytic medicationsA term used to describe the medical interruption and halting of contractions during premature labor.Visit our comprehensive glossary for more pregnancy terms and definitions. medications, your doctor will want to check your medical record to make sure you are healthy.

Checklist for administering tocolytic medications

history of heart disease

history of diabetes mellitus

chronic hypertension and signs of preeclampsia

correct pregnancy location

severe placental problems

infection of the amniotic fluid

the baby is alive and well

congenital abnormalities

hyperthyroidism (Grave's disease)

dilated cervix

If your doctor feels that premature labor may cause you or your baby more harm than the tocolytic medications, then they may still be administered. Labor after week thirty five will not be arrested if your membranes have ruptured and your cervix has dilated more than four centimetres. An L/S ratio and phosphatidyl glycerol test will be performed to check the maturity of your baby's lungs.

No results found. Click here for amazon.comThere is no evidence of an increased risk of congenital abnormalities or developmental problems as a result of using ritodrine, terbutaline or magnesium sulfate. If your baby is delivered within twenty four hours of treatment using either ritodrine or terbutaline, its blood glucose level will be monitored for hypoglycemia, or low blood sugar. A sugar solution will be administered if necessary. Magnesium sulfate therapy may result in poor muscle tone during the first two hours after delivery.

Ritodrine and terbutaline may affect you for a day or two after treatment. While not dangerous you may experience increased heart rate, nausea and vomiting, headaches, insomnia, water retention in the lungs resulting in chest pains and breathlessness or dyspnea. You may experience similar side effects from magnesium sulfate therapy including fever, headaches, nausea and constipation.

If you show signs of infection you may be given an antibiotic before the tocolytic drugs are administered. Pain and anxiety may be reasons for your doctor to give you a mild sedative or antianxiety medication. Sometimes these medications used in combination with fluid administered intravenously can be enough to calm your contractions. Your doctor may consider using morphine or pethidine, but these drugs can aggravate the uterus and have a negative effect on your baby and are only used in cases of extreme pain.

After your labor has been stopped there are three different options for management. The treatment you receive will depend on your doctor's personal preference and other factors. If drugs were administered, you may remain in hospital for additional rest and observation for a couple of days. Your doctor may decide to let you return home, while you take oral tocolytic medication or receive terbutaline from a pump through a needle placed in the fat under your skin. Depending on your condition and the stage of pregnancy your doctor may recommend home uterine activity monitoring.

If labor cannot be stopped

After the membranes have ruptured it is unlikely that labor can be arrested. Since there is an increased risk of infection, your doctor will recommend that you go to the hospital, where you will be monitored and given antibiotics if needed. The hospital will also be equipped with a neonatal intensive care unitPart of a hospital that is dedicated to the care and attention of newborn infants that are seriously ill or premature. It contains a variety of specialized equipment and is staffed by a team of nurses and neonatologists who are specially trained in the pathophysiology of the newborn.Visit our comprehensive glossary for more pregnancy terms and definitions. or NICU, which is capable of providing the necessary care to your premature baby after delivery.

No results found. Click here for amazon.comBecause the baby's head is smaller and softer when premature, labor is generally shorter and easier than a full term delivery. An episiotomyA surgical procedure in which an incision is made in the perineum to enlarge the vaginal opening and faciliate delivery of the baby or prevent tearing of the perineum. It is closed with absorbable sutures.There are two types of episiotomy; the medilateral, cut at 45 degrees with midline, and median cut in the midline. The former offers more room for delivery but is more painful postpartum, while the latter heals more easily, but provides less room for delivery.Visit our comprehensive glossary for more pregnancy terms and definitions. will probably be performed, and forceps used for delivery to protect your baby from pressure changes in the birth canal.

If there are no signs of contractions within one or two days, an oxytocinOxytocin is a pregnancy hormone that both stimulates breast milk production and stimulates uterine contractions. Synthetic oxytocins have been created to induce labor.Visit our comprehensive glossary for more pregnancy terms and definitions. will be administered to stimulate labor. You will probably be given an epiduralA regional anesthetic introduced into the base of the spine used during labor and for cesarean sections. Also known as an epidural block.Visit our comprehensive glossary for more pregnancy terms and definitions. instead of analgesic medicationsA form of painkilling agent that doesn't induce unconciousness in the patient.Visit our comprehensive glossary for more pregnancy terms and definitions., which can depress the baby's respiratory sytem. Your baby will be closely monitored for signs of fetal distressA condition, usually discovered in labor, in which the fetal heartbeat follows an abnormal pattern. The fetal heartbeat is recorded using electronic fetal monitoring.The acid balance of the fetal blood is measured, and labor is allowed to continue if it falls within prescribed ranges, and the abnormal heartbeat does not recur or persist.If nescessary, attempts will be made to stabilize the fetus by administering oxygen to the mother, increasing her fluid intake or prescribing an agent to help the uterus relax. In some cases a cesarean section may be required.Visit our comprehensive glossary for more pregnancy terms and definitions. resulting from a lack of oxygen, using electronic fetal monitoring and if necessary a cesarean section will be performed.

Malpositions and malpresentations

Malpositions are abnormal positions of the vertex of the fetal head (with the occiput as the reference point) relative to the maternal pelvis. Malpresentations are all presentations of the fetus other than vertex.

PROBLEM

The fetus is in an abnormal position or presentation that may result in prolonged or obstructed labour.

GENERAL MANAGEMENT

Make a rapid evaluation of the general condition of the woman including vital signs (pulse, blood pressure, respiration, temperature).

Assess fetal condition:

- Listen to the fetal heart rate immediately after a contraction:

- Count the fetal heart rate for a full minute at least once every 30 minutes during the active phase and every 5 minutes during the second stage;

- If there are fetal heart rate abnormalities (less than 100 or more than 180 beats per minute), suspect fetal distress.

- If the membranes have ruptured, note the colour of the draining amniotic fluid:

- Presence of thick meconium indicates the need for close monitoring and possible intervention for management of fetal distress;

- Absence of fluid draining after rupture of the membranes is an indication of reduced volume of amniotic fluid, which may be associated with fetal distress.

Provide encouragement and supportive care.

Review progress of labour using a partograph.

Note: Observe the woman closely. Malpresentations increase the risk for uterine rupture because of the potential for obstructed labour.

DIAGNOSIS

DETERMINE THE PRESENTING PART

The most common presentation is the vertex of the fetal head. If the vertex is not the presenting part, see Table S-12.

If the vertex is the presenting part, use landmarks of the fetal skull to determine the position of the fetal head (Fig S-9).

Figure S-9

Landmarks of the fetal skull

DETERMINE THE POSITION OF THE FETAL HEAD

The fetal head normally engages in the maternal pelvis in an occiput transverse position, with the fetal occiput transverse in the maternal pelvis (Fig S-10).

Figure S-10

Occiput transverse positions

With descent, the fetal head rotates so that the fetal occiput is anterior in the maternal pelvis (Fig S-11). Failure of an occiput transverse position to rotate to an occiput anterior position should be managed as an occiput posterior position.

Figure S-11

Occiput anterior positions

An additional feature of a normal presentation is a well-flexed vertex (Fig S-12), with the fetal occiput lower in the vagina than the sinciput.

Figure S-12

Well-flexed vertex

If the fetal head is well-flexed with occiput anterior or occiput transverse (in early labour), proceed with delivery.

If the fetal head is not occiput anterior, identify and manage the malposition (Table S-11).

If the fetal head is not the presenting part or the fetal head is not well-flexed, identify and manage the malpresentation (Table S-12).

TABLE S-11 Diagnosis of malpositions

TABLE S-12 Diagnosis of malpresentations

MANAGEMENT

OCCIPUT POSTERIOR POSITIONS

Spontaneous rotation to the anterior position occurs in 90% of cases. Arrested labour may occur when the head does not rotate and/or descend. Delivery may be complicated by perineal tears or extension of an episiotomy.

If there are signs of obstruction or the fetal heart rate is abnormal (less than 100 or more than 180 beats per minute) at any stage, deliver by caesarean section.

If the membranes are intact, rupture the membranes with an amniotic hook or a Kocher clamp.

If the cervix is not fully dilated and there are no signs of obstruction, augment labour with oxytocin.

If the cervix is fully dilated but there is no descent in the expulsive phase, assess for signs of obstruction (Table S-10):

- If there are no signs of obstruction, augment labour with oxytocin.

If the cervix is fully dilated and if:

- the fetal head is more than 3/5 palpable above the symphysis pubis or the leading bony edge of the head is above -2 station, perform caesarean section;

- the fetal head is between 1/5 and 3/5 above the symphysis pubis or the leading bony edge of the head is between 0 station and -2 station:

- Delivery by vacuum extraction and symphysiotomy;

- If the operator is not proficient in symphysiotomy, perform caesarean section;

- the head is not more than 1/5 above the symphysis pubis or the leading bony edge of the fetal head is at 0 station, deliver by vacuum extraction or forceps.

BROW PRESENTATION

In brow presentation, engagement is usually impossible and arrested labour is common. Spontaneous conversion to either vertex presentation or face presentation can rarely occur, particularly when the fetus is small or when there is fetal death with maceration. It is unusual for spontaneous conversion to occur with an average-sized live fetus once the membranes have ruptured.

If the fetus is alive, deliver by caesarean section.

If the fetus is dead and:

- the cervix is not fully dilated, deliver by caesarean section;

- the cervix is fully dilated:

- Deliver by craniotomy;

- If the operator is not proficient in craniotomy, deliver by caesarean section.

Do not deliver brow presentation by vacuum extraction, outlet forceps or symphysiotomy.

FACE PRESENTATION

The chin serves as the reference point in describing the position of the head. It is necessary to distinguish only chin-anterior positions in which the chin is anterior in relation to the maternal pelvis (Fig S-24 A) from chin-posterior positions (Fig S-24 B).

Figure S-24

Face presentation

Prolonged labour is common. Descent and delivery of the head by flexion may occur in the chin-anterior position. In the chin-posterior position, however, the fully extended head is blocked by the sacrum. This prevents descent and labour is arrested.

CHIN-ANTERIOR POSITION

If the cervix is fully dilated:

- Allow to proceed with normal childbirth;

- If there is slow progress and no sign of obstruction (Table S-10), augment labour with oxytocin;

- If descent is unsatisfactory, deliver by forceps.

If the cervix is not fully dilated and there are no signs of obstruction, augment labour with oxytocin. Review progress as with vertex presentation.

CHIN-POSTERIOR POSITION

If the cervix is fully dilated, deliver by caesarean section.

If the cervix is not fully dilated, monitor descent, rotation and progress. If there are signs of obstruction, deliver by caesarean section.

If the fetus is dead:

- Deliver by craniotomy;

- If the operator is not proficient in craniotomy, deliver by caesarean section.

Do not perform vacuum extraction for face presentation.

COMPOUND PRESENTATION

Spontaneous delivery can occur only when the fetus is very small or dead and macerated. Arrested labour occurs in the expulsive stage.

Replacement of the prolapsed arm is sometimes possible:

- Assist the woman to assume the knee-chest position (Fig S-25);

- Push the arm above the pelvic brim and hold it there until a contraction pushes the head into the pelvis.

- Proceed with management for normal childbirth.

Figure S-25

Knee-chest position

If the procedure fails or if the cord prolapses, deliver by caesarean section.

BREECH PRESENTATION

Prolonged labour with breech presentation is an indication for urgent caesarean section. Failure of labour to progress must be considered a sign of possible disproportion (Table S-10)

The frequency of breech presentation is high in preterm labour.

EARLY LABOUR

Ideally, every breech delivery should take place in a hospital with surgical capability.

Attempt external version if:

- breech presentation is present at or after 37 weeks (before 37 weeks, a successful version is more likely to spontaneously revert back to breech presentation);

- vaginal delivery is possible;

- membranes are intact and amniotic fluid is adequate;

- there are no complications (e.g. fetal growth restriction, uterine bleeding, previous caesarean delivery, fetal abnormalities, twin pregnancy, hypertension, fetal death).

If external version is successful, proceed with normal childbirth.

If external version fails, proceed with vaginal breech delivery (see below) or caesarean section.

VAGINAL BREECH DELIVERY

A vaginal breech delivery by a skilled health care provider is safe and feasible under the following conditions:

- complete (Fig S-20) or frank breech (Fig S-21);

- adequate clinical pelvimetry;

- fetus is not too large;

- no previous caesarean section for cephalopelvic disproportion;

- flexed head.

Examine the woman regularly and record progress on a partograph.

If the membranes rupture, examine the woman immediately to exclude cord prolapse.

Note: Do not rupture the membranes.

If the cord prolapses and delivery is not imminent, deliver by caesarean section.

If there are fetal heart rate abnormalities (less than 100 or more than 180 beats per minute) or prolonged labour, deliver by caesarean section.

Note: Meconium is common with breech labour and is not a sign of fetal distress if the fetal heart rate is normal.

The woman should not push until the cervix is fully dilated. Full dilatation should be confirmed by vaginal examination.

CAESAREAN SECTION FOR BREECH PRESENTATION

A caesarean section is safer than vaginal breech delivery and recommended in cases of:

- double footling breech;

- small or malformed pelvis;

- very large fetus;

- previous caesarean section for cephalopelvic disproportion;

- hyperextended or deflexed head.

Note: Elective caesarean section does not improve the outcome in preterm breech delivery.

COMPLICATIONS

Fetal complications of breech presentation include:

cord prolapse;

birth trauma as a result of extended arm or head, incomplete dilatation of the cervix or cephalopelvic disproportion;

asphyxia from cord prolapse, cord compression, placental detachment or arrested head;

damage to abdominal organs;

broken neck.

TRANSVERSE LIE AND SHOULDER PRESENTATION If the woman is in early labour and the membranes are intact, attempt external version:

- If external version is successful, proceed with normal childbirth;

- If external version fails or is not advisable, deliver by caesarean section (page P-43).

Monitor for signs of cord prolapse. If the cord prolapses and delivery is not imminent, deliver by caesarean section.

Note: Ruptured uterus may occur if the woman is left unattended .

In modern practice, persistent transverse lie in labour is delivered by caesarean section whether the fetus is alive or dead.

Top of page User's surveyGive us your feedback on the manual Reply to the user's survey (Deadline: 31.07.2007)Clinical principles

Rapid initial assessment

Talking with women and their familiesEmotional and psychological supportEmergenciesGeneral care principlesClinical use of blood, blood productsand replacement fluidsAntibiotic therapyAnaesthesia and analgesiaOperative care principlesNormal Labour and childbirthNewborn care principlesProvider and community linkagesSymptomsShockVaginal bleeding in early pregnancyVaginal bleeding in later pregnancy and labourVaginal bleeding after childbirthHeadache, blurred vision, convulsions or loss of consciousness, elevated blood pressureUnsatisfactory progress of LabourMalpositions and malpresentationsShoulder dystociaLabour with an overdistended uterusLabour with a scarred uterusFetal distress in LabourProlapsed cordFever during pregnancy and labourFever after childbirthAbdominal pain in early pregnancyAbdominal pain in later pregnancy and after childbirthDifficulty in breathingLoss of fetal movementsPrelabour rupture of membranesImmediate newborn conditions or problemsProceduresParacervical blockPudendal blockLocal anaesthesia for caesaran sectionSpinal (subarachnoid) anaesthesiaKetamineExternal versionInduction and augmentation of labourVacuum extractionForceps deliveryCaesarean sectionSymphysontomyCraniotomy and craniocentesisDilatation and curettageManual vacuum aspirationCuldocentesis and colpotomyEpisiotomyManual removal of placentaRepair of cervical tearsRepair of vaginal and perinetal tearsCorrecting uterine inversionRepair of ruptured uterusUterine and utero-ovarian artery ligationPostpartum hysterectomySalpingectomy for ectopic pregnancuyAppendixEssential drugs for managing complications in pregnancy and childbirthIndex

PrematurityIn that they continue developing after birth, most animals are born not mature. At birth, a normal human infant is relatively less mature than infants of some other primate species, possibly to allow its disproportionately large head to fit through a pelvis adapted for walking on two legs.

In humans, whereas the usual definition of preterm birth is birth before 37 weeks gestation,[2] a "premature" infant is one that has not yet reached the level of fetal development that generally allows life outside the womb. In the normal human fetus, several organ systems mature between 34 and 37 weeks, and the fetus reaches adequate maturity by the end of this period. One of the main organs greatly affected by premature birth is the lungs. The lungs are one of the last organs to develop in the womb; because of this, preemies typically spend the first days/weeks of their life on a ventilator. Therefore, a significant overlap exists between preterm birth and prematurity: generally, preterm babies are premature and term babies are mature. Prematurity can be reduced to a small extent by using drugs to accelerate maturation of the fetus, and to a greater extent by preventing preterm birth.

EpidemiologyIn Europe and many developed countries the preterm birth rate is generally 5-9%, and in the USA it has even risen to 12-13% in the last decades.[1] Three obstetric events precede preterm birth: spontaneous preterm births are the 40-45% preterm births that follow preterm labor and the 25-30% preterm births after premature rupture of membranes. The remainder (30-35%) are preterm births that are induced for obstetrical reasons; obstetricians may have to deliver the baby preterm because of a deteriorating intrauterine environment (i.e. infection, intrauterine growth retardation) or significant endangerment of the maternal health (i.e. preeclampsia, cancer). By gestational age, 5% of preterm births occur at less than 28 weeks (extreme prematurity), 15% at 28-31 weeks (severe prematurity), 20% at 32-33 weeks (moderate prematurity), and 60-70% at 34-36 weeks (near term).[1]As weight is easier to determine than gestational age, the World Health Organization tracks rates of low birth weight (< 2,500 grams), which occurred in 16.5 percent of births in less developed regions in 2000.[3] It is estimated that one-third of these low birth weight deliveries are due to preterm delivery. Weight generally correlates to gestational age, however, infants may be underweight for other reasons than a preterm delivery. Neonates of low birth weight (LBW) have a birth weight of less than 2500 g (5 lb 8 oz) and are mostly but not exclusively preterm babies as they also include small for gestational age (SGA) babies. Weight-based classification further recognizes Very Low Birth Weight (VLBW) which is less than 1500 g, and Extremely Low Birth Weight (ELBW) which is less than 1000 g.[4] Almost all neonates in these latter two groups are born preterm.

Preterm birth is a significant cost factor in healthcare, not even considering the expenses of long-term care for individuals with disabilities due to preterm birth. A 2003 study in the US determined neonatal costs to be $224,400 for a newborn at 500-700 g versus $1,000 at over 3,000 g. The costs increase exponentially with decreasing gestational age and weight.[5]Epidemiology The frequency of preterm births is about 5-9% in many developed countries and around 12-13% in the USA. The rate of preterm birth has increased in many locations predominantly because of increasing preterm delivery of artificially conceived multiple pregnancies.2About 7% of babies in the UK weigh less than 2.5 kg at birth, rising to 10% in deprived areas such as Hackney.3

Simply labelling all babies born before 37 weeks as premature fails to illustrate the marked gradation in terms of severity of the problem with increasing prematurity:

A baby born at 36 weeks will probably be a little slow to feed.

A baby born before 33 weeks will have more serious problems including, possibly, immature lungs.

Birth before 28 weeks causes very significant problems but the survival rate is quite remarkable.

Quoting figures may be misleading as they will vary considerably amongst units but figures that are not atypical include 90% survival if over 800g, 50% survival if over 500g and 80% survival before 28 weeks. These figures may also hide significant disability in survivors.

Risk factors for premature delivery

There are a number of risk factors for early delivery:

Induction or caesarean section may have been undertaken because of serious adverse intrauterine conditions:

This may include fulminating pre-eclampsia or abruptio placentae.

The decision that has to be made is "Is the baby safer in or out?" This is a matter of balancing risks.

Caesarean delivery is not associated with either reduced mortality or neuro-disability at two years of age. It is advised therefore that the method of delivery of these infants should be based on obstetric or maternal indications rather than the perceived outcome of the baby.4

Multiple pregnancy often leads to premature labour and this may be very early if multiple means more than twins.

Other causes of a large uterus e.g. polyhydramnios.

The classical story of cervical incompetence is one of progressively earlier labours in successive pregnancies with premature rupture of membranes and a painless early dilation of the cervix.

Low socio-economic status, inadequate or absent antenatal care and poor maternal nutrition all predispose to premature labour. Low body mass index and periodontal disease are associated with premature delivery.2

African-American and Afro-Caribbean women are two to three times more likely to deliver early than white women. However, not all of this difference can be explained by socioeconomic factors - gene/environment interactions are a factor.5

Smoking and excessive alcohol consumption are also risk factors.

Heroin withdrawal or too rapid reduction of methadone during the last trimester can induce premature labour:

Drug abusers must be encouraged to comply closely with their regimen and reduction of methadone should be slow in the last trimester.

Cocaine can also cause premature labour. It is a potent vasoconstrictor and this can have a devastating effect on placental function.

Maternal age under 17 or over 35 years old.

Bacterial vaginosis predisposes to premature labour.

Presentation

The premature baby will look small and unprepared for this world. The baby who is also SFD may have little subcutaneous fat and the skin may appear wrinkled.

Because mortality rates have fallen, the focus for perinatal interventions is to reduce long-term morbidity, especially the prevention of brain injury and abnormal brain development. The premature baby faces a number of problems (these may be accentuated if there is also IUGR):

Hypothermia is a great risk, especially if there is little subcutaneous fat. A premature baby is less able to shiver and to maintain homeostasis.

Hypoglycaemia is also a risk, especially if SFD. There may also be hypocalcaemia. Both can cause convulsions that may produce long term brain damage.

The more premature the baby, the greater the risk of respiratory distress syndrome. Steroids before delivery may reduce the risk but it is still very real. If the baby requires oxygen it must be monitored very carefully as if the levels are too high the premature baby is susceptible to retrolental fibroplasia and blindness.

The premature baby is more susceptible to neonatal jaundice and to kernicterus at a lower level of bilirubin than a more mature baby.

They are susceptible to infection and to necrotising enteritis.

They are susceptible to intraventricular brain haemorrhage with serious long term effects.

All these are problems faced by the neonatologist in the Special Care Baby Unit but when the baby is eventually discharged from hospital and goes home with the family, that is not the end of problems. The baby who is just slightly premature will probably have little on no long term problems but those who are very premature and who have a stormy start to life often suffer many and serious problems.

Supporting the parents

When a baby is in SCBU it is a very emotional and traumatic time for both the parents, not just the mother. They should be encouraged to visit and stay with the baby as much as possible. Breastfeeding may be rather difficult but it should be encouraged.6 Breastmilk is the best food for any baby but especially premature babies. Mothers who are producing more than their own baby needs should be encouraged to donate to the local SCBU as it is always welcome.

The baby is attached to monitors and has tubes in and out of the body. It may not be possible to hold the baby or it may not be possible to do so for long. This should be encouraged as much as is compatible with the safety of the baby but bonding is much more difficult than with a normal, healthy, full term baby.

Whilst trying to keep a positive attitude, the parents must also come to terms with the fact that the baby could die. There may also be difficult decisions about switching off ventilators and the expected quality of life if the child survives. Communicating in these situations can be difficult and parents may have trouble taking in what they are told at such an emotional time.7 They may wish to discuss matters with the familiar face of their family doctor who is outside the hospital but who understands the issues involved.

Immunisations

Premature babies need to be protected by immunisations as much as any other baby and prematurity is not a contraindication to immunisation even if the immune system may be immature. The timing of immunisations is based on the child's chronological age from birth and not on the child's putative age based on maturity.8Long term problems of premature babies

Morbidity is inversely related to gestational age; however, there is no gestational age (including term) that is wholly exempt.9 Severe problems such as cerebral palsy, blindness and deafness may affect as many as 10 to 15% of significantly premature babies. There is some evidence that the incidence of cerebral palsy is falling in premature babies born between 28-31 weeks.10Figures about outcomes for premature babies have to be interpreted with a degree of circumspection to be sure that like is being compared with like:

Percentages should be taken with caution.

Different studies use different criteria for the degree of prematurity for inclusion.

There is a gradation of risk.

Being both premature and small for dates would seem to add further to the risk.

Sight and hearing

About 1 in 4 babies with birth weight below 1.5 kg has peripheral or central hearing impairment or both.11

Infants who undergo early screening and treatment for retinopathy of prematurity have improved long-term functional and structural outcomes compared with those who receive conventional screening and treatment.12 However, the increased survival of lower birth weight infants has increased the prevalence of aggressive, posterior retinopathy of prematurity that may be unresponsive to conventional treatment.In a multicentre study 66% of babies under 1.25 kg developed ROP, but only 6% required treatment.13Follow up to school

Cognitive and neuromotor impairments at 5 years of age increase with decreasing gestational age. Many of these children need a high level of specialised care:14

About half of infants born at 2428 weeks of gestation have a disability at 5 years, similar to the proportion observed in the UK-based EPICure study.15

In the infants born later (2932 weeks' gestation), about a third have a disability at 5 years.

Behavioural and psychomotor problems

A study from Liverpool has looked at children of 7 and 8 who were born before 32 weeks and who were well enough to attend mainstream school.16 They were compared with full-term children of similar age in their class at school:

Disabilities can be subtle and numerous and so a range of tests was used.

The preterm children had a higher incidence of motor impairment and this affected how well they did at school even when their intelligence was normal.

Over 30% had developmental coordination disorder (DCD) compared with 6% of classmates.

The preterm children were significantly more likely be overactive, easily distractible, impulsive, disorganised and lacking in persistence. They also tended to overestimate their ability.

Attention deficit hyperactivity disorder (ADHD) was found in 8.9% of the preterm children and 2% of controls.

The children who had been the most premature were not necessarily those with the lowest scores.

Although major disabilities have been reduced, the levels of disability tested in this study did not seem lower than those found in children born 10 or 20 years earlier, despite improvements in care of the newborn.

Brain development

IUGR may be very important in terms of early growth of the brain leading to poor IQ and developmental skills.17 Individuals who were born before 33 weeks gestation continue to show noticeable decrements in brain volumes and striking increases in lateral ventricular volume into adolescence.18Emotional development - teens and beyond

A study of teenagers in mainstream schools who were born before 29 weeks gestation showed that compared with mainstream classmates, they have higher levels of parent and teacher reported emotional, attentional, and peer problems well into their teens. Despite these problems, they do not show signs of more serious conduct disorders, delinquency, drug use, or depression.19

A study of 18 and 19 years olds who were born before 33 weeks gestation showed that they had different personalities from controls with increased neuroticism and decreased extraversion scores. This was more marked in females than males.13

A study of pre-term children who had reached 19 to 22 years of age showed that they were, on average, shorter than their contemporaries, more likely to use prescription medicines and less likely to have attended higher education.20Prevention

Interventions to reduce the morbidity and mortality of preterm birth can be primary (directed to all women), secondary (aimed at eliminating or reducing existing risk), or tertiary (intended to improve outcomes for preterm infants).21 Most efforts so far have been tertiary interventions.

Primary - Problems of social deprivation, poor maternal nutrition and substance abuse must all be addressed. Smoking should cease and, as explained in the article on fetal alcohol syndrome, alcohol consumption should be avoided as there may be no safe lower limit.22

Secondary - Antenatal care is important and should be easily accessible to all women.

Tertiary - Interventions when complications arise e.g. regionalised care, treatment with antenatal corticosteroids, tocolytic agents and antibiotics.

Ethical issues

The success of improved survival in very premature infants has raised some serious ethical issues. It is now possible to save more and more smaller and earlier babies but is this a good thing?

Such babies have a very high incidence of both physical and behavioural problems. This may be blindness, deafness, mental handicap or ADHD. Is the quality of life really worth the enormous input?

The term bed blockers is usually used pejoratively of the elderly but tiny, very early babies spend a very long time in SCBU cots that are in short supply. They may be depriving other babies of facilities from which they would extract greater benefit. The cost of SCBU care is also very high and finance is not a limitless resource.

However, premature babies can become extremely productive, as shown by the list of famous premature babies on the premature babies uk website. It includes Albert Einstein, Isaac Newton and Charles Darwin.

When should neonatologists decide that the quality of life that they salvage is not worthy of the effort? When would it be better to let tiny babies die? This is a very difficult question that will raise much passion and prejudice but it is an extremely important issue that does require sober assessment.

The high survival rates that are achieved by some units for very premature babies has fuelled a debate about the upper limit for termination of pregnancy.

Signs and symptomsSymptoms of imminent spontaneous preterm birth are signs of premature labor; such signs consists of four or more uterine contractions in one hour before 37 weeks' gestation. In contrast to false labor, true labor is accompanied by cervical shortening and effacement. Also, vaginal bleeding in the third trimester, heavy pressure in the pelvis, or abdominal or back pain could be indicators that a preterm birth is about to occur. A watery discharge from the vagina may indicate premature rupture of the membranes that surround the baby. While the rupture of the membranes may not be followed by labor, usually delivery is indicated as infection (chorioamnionitis) is a real threat to both, fetus and mother. In some cases the cervix dilates prematurely without pain or perceived contractions, so that the mother may not have warning signs until very late in the birthing process.

CausesAs the cause of labor still remains elusive, the exact cause of preterm birth is also unsolved. Labor is a complex process involving many factors. Four different pathways have been identified that can result in preterm birth and have considerable evidence: precocious fetal endocrine activation, uterine overdistension, decidual bleeding, and intrauterine inflammation/infection.[6] Activation of one or more of these the these pathways may have been gradually over weeks, even months.[6] From a practical point a number of factors have been identified that are associated with preterm birth, however, an association does not establish causality.

Maternal backgroundA number of factors have been identified that are linked to a higher risk of a preterm birth: low socio-economic or educational standing and single motherhood,[1] as well as age at the upper and lower end of the reproductive years be it more than 35[7] or less than 18 years of age.[1] Further, in the US and the UK Afro-American and Afro-Caribbean women have preterm birth rates of 15-18% more than double than that of the white population. This discrepancy is not seen in comparison to Asian or Hispanic immigrants and remains unexplained.[1]Pregnancy interval makes a difference as women with a 6 months span or less between pregnancies have a two-fold increase in preterm birth.[8] Studies on type of work and physical activity have given conflicting results, but it is opined that stressful conditions, hard labor, and long hours are probably linked to preterm birth.[1] Patients who had undergone previous induced abortions have been shown to have a higher risk of preterm birth only if the termination was performed surgically but not medically.[9] Adequate maternal nutrition is important. Women with a low BMI are at increased risk for preterm birth.[10] Further, women with poor nutritional status may also be deficient in vitamins and minerals. Adequate nutrition is critical for fetal development and a diet low in saturated fat and cholesterol may help reduce the risk of a preterm delivery.[11] Obesity does not directly lead to preterm birth; however, it is associated with diabetes and hypertension which are risk factors by themselves.[1] Women with a previous preterm birth are at higher risk for a recurrence at a rate of 15-50% depending on number of previous events and their timing.[12] To some degree those individuals may have underlying conditions (i.e. uterine malformation, hypertension, diabetes) that persist. Genetic make-up is a factor in the causality of preterm birth. An intra- and transgenerational increase in the risk of preterm delivery has been demonstrated.[13]

HYPERLINK "http://en.wikipedia.org/wiki/" \l "cite_note-13" [14] No single gene has been identified, and it appears with the complexity of the labor initiation, that numerous polymorphic genetic interactions are possible.

Factors during pregnancyMultiple pregnancies (twins, triplets, etc.) are a significant factor in preterm birth. The March of Dimes Multicenter Prematurity and Prevention Study found that 54% of twins were delivered preterm vs. 9.6% of singleton births.[15] Triplets and more are even more endangered. The use of fertility medication that stimulates the ovary to release multiple eggs and of IVF with embryo transfer of multiple embryos has been implicated as an important factor in preterm birth. Maternal medical conditions increase the risk of preterm birth, and often labor has to be induced for medical reasons; such conditions include high blood pressure[16], pre-eclampsia[17], maternal diabetes[18], asthma, thyroid disease, and heart disease. In a number of women anatomical issues prevent that the baby is carried to term. Some women have a weak or short cervix[16] (the strongest predictor of premature birth)[19]

HYPERLINK "http://en.wikipedia.org/wiki/" \l "cite_note-Fonseca-p462-19" [20]

HYPERLINK "http://en.wikipedia.org/wiki/" \l "cite_note-Romero-675-20" [21] The cervix may also have been compromised by previous cervical conization or loop excision. In women with uterine malformations the capacity of the uterus to hold the growing pregnancy may be limited and preterm labor ensues.[22] Women with vaginal bleeding during pregnancy are at higher risk for preterm birth. While bleeding in the third trimester may be a sign of placenta previa or placental abruption conditions that occur frequently preterm even earlier bleeding that is not caused by these two conditions is linked to a higher preterm birth rate.[23] Women with abnormal amounts of amniotic fluid, too much (polyhydramnios) or too little (oligohydramnios) are also at risk.[1] The mental status of the women is of significance. Anxiety[24] and depression have been linked to preterm birth.[1] Finally, the use of tobacco, cocaine, and excessive alcohol during pregnancy also increases the chance of preterm delivery. Tobacco is the most commonly abused drug during pregnancy and also contributes significantly to low birth weight delivery.[25]

HYPERLINK "http://en.wikipedia.org/wiki/" \l "cite_note-25" [26] Babies with birth defects are at higher risk of being born preterm.[27]InfectionInfections play a major role in the genesis of preterm birth and may account for 25-40% of events.[28] The frequency of infection in preterm birth is inversely related to the gestational age.[1] Endotoxins released by microorganisms and cytokines stimulate deciduasl responses including the release of prostaglandins which may stimulate uterine contractions. Further the decidual response may include release of matrix-degrading enzymes that weaken fetal membranes leading to premature rupture.[28] Intrauterine infection appears to be a chronic process.[28] Typical organisms identified in the uterus before rupture of the membranes are genital Mycoplasma spp and specifically Ureaplasma urealyticum. Micro-organisms may reach the decidua in a number of ways, ascending, hematogeneous, iatrogenic by a procedure, or retrograde through the fallopian tubes. From the deciduas they may reach the space between the amnion and chorion, the amniotic fluid, and finally the fetus. A chorioamnionitis also may lead to sepsis of the mother. Fetal infection not only is linked to preterm birth but to significant long-term handicap including cerebral palsy.[1] It has been reported that asymptomatic colonization of the decidua occurs in up to 70% of women at term using a DNA probe suggesting that the presence of micro-organism alone may be insufficient to initiate the infectious response. Bacterial vaginosis has been linked to preterm birth raising the risk by a factor of 1.5 - 3.[29] As the condition is more prevalent in black women in the US and the UK, it has been suggested to be an explanation for the higher rate of preterm birth in this population. It is opined that bacterial vaginosis before or during pregnancy may affect the decidual inflammatory response that leads to preterm birth.[1] A number of maternal bacterial infections are associated with preterm birth including pyelonephritis, asymptomatic bacteriuria, pneumonia, and appendicitis. Also periodontal disease has been shown repeatedly to be linked to preterm birth.[30] In contrast, viral infections, unless accompanied by a significant febrile response, are considered not to be a major factor in relation to preterm birth.[1]Clinical testsHelpful clinical test should predict a high risk for preterm birth during the early and middle part of the third trimester, when their impact is significant. Many women experience false labor (not leading to cervical shortening and effacement) and are falsely labelled to be in preterm labor. The study of preterm birth has been hampered by the difficulty in distinguishing between "true" preterm labor and false labor.[6] These new test are used to identify women at risk for preterm birth.

Fetal fibronectinFetal fibronectin has become the most important biomarker the presence of this glycoprotein in the cervical or vaginal secretions indicates that the border between the chorion and deciduas has been disrupted. A positive test indicates an increased risk of preterm birth, and a negative test has a high predictive value.[1] It has been shown that only 1% of women in questionable cases of preterm labor delivered within the next week when the test was negative.[31]Ultrasonography of the cervixObstetric ultrasound has become useful in the assessment of the cervix in women at risk for premature delivery. A short cervix preterm is undesirable: At 24 weeks gestation a cervix length of less than 25mm defines a risk group for preterm birth. Further, the shorter the cervix the greater the risk.[32] It also has been helpful to use ultrasonography in women with preterm contractions, as those whose cervix length exceeds 30mm are unlikely to deliver within the next week.[33]InterventionHistorically efforts have been primarily aimed to improve survival and health of preterm infants (tertiary intervention). Such efforts, however, have not reduced the incidence of preterm birth. Increasingly primary interventions that are directed at all women, and secondary intervention that reduce existing risks are looked upon as measures that need to be developed and implemented to prevent the health problems of premature infants and children.[34]Primary (aimed at all women)PreconceptionalRaising public and professional awareness about the scope of the problem and its significance as the major contributor to infant mortality is a beginning to reduce avoidable risk factor. Among them is the need to reduce repeated uterine instrumentation ( ie repeated surgical abortions)[35] and to avoid risky choices in infertility treatments. Adoption of specific professional policies can immediately reduce risk of preterm birth as the experience in assisted reproduction has shown when the number of embryos during embryo transfer were limited.[34] Society has established in many countries programs specifically to protect pregnant women from hazardous work and night shift and provided time for prenatal visits and paid pregnancy-leave. The EUROPOP study showed that preterm birth is not related to type of employment, but to prolonged work (>42 h per week) or prolonged standing (>6 h per day).[36] Also, night work has been linked to preterm birth.[37] Health policies that take these findings into account can be expected to reduce the rate of preterm birth.[34] Avoidance of weight extremes and good nutritional support are important. Although a study failed to show that multivitamin preparation taken prior to conception reduces the risk of preterm birth,[38] preconceptional intake of folic acid is recommended to reduce birth defects. There is some evidence that long term (> one year) use of folic acid may reduce premature birth.[39]

HYPERLINK "http://en.wikipedia.org/wiki/" \l "cite_note-39" [40] Reducing smoking is expected to benefit pregnant women and their offspring.[34]During pregnancyInterventions that should have been initiated prior to pregnancy, can still be instituted during pregnancy including nutritional adjustments, use of vitamin supplements, and smoking cessation.[34] Calcium supplementation as well as supplemental intake of C and E vitamins could not be shown to reduce preterm birth rates.[41]

HYPERLINK "http://en.wikipedia.org/wiki/" \l "cite_note-41" [42] Different strategies are used in the administration of prenatal care, and future studies need to determine if the focus should be on screening for high risk women, or widened support for low-risk women, or to what degree these approaches should be merged.[34] While periodontal infection has been linked with preterm birth, randomized trials have not shown that periodontal care during pregnancy reduces preterm birth rates.[34]Screening of low risk womenScreening for asymptomatic bacteriuria followed by appropriate treatment reduces pyelonephritis and reduces the risk of preterm birth.[43] Extensive studies have been carried out to determine if other forms of screening in low-risk women followed by appropriate intervention are beneficial, including: Screening for and treatment of Ureaplasma urealyticum, group B streptococcus, Trichomonas vaginalis, and bacterial vaginosis did not reduce the rate of preterm birth.[34] Routine ultrasound examination of the length of the cervix identifies patients at risk, but cerclage is not proven useful, and the application of a progesterone is under study.[34] Screening for the presence of fibronectin in vaginal secretions is not recommended at this time in women at low risk.

Self-careSelf-care methods to reduce the risk of preterm birth include proper nutrition, avoiding stress, seeking appropriate medical care, avoiding infections, and the control of preterm birth risk factors (e.g. working long hours while standing on feet, carbon monoxide exposure, domestic abuse, and other factors). Self-monitoring vaginal pH followed by yogurt treatment or clindamycin treatment if the pH was too high all seem to be effective at reducing the risk of preterm birth.[44]

HYPERLINK "http://en.wikipedia.org/wiki/" \l "cite_note-44" [45] Secondary (reducing existing risks)Women are identified to be at increased risk for preterm birth on the basis of their past obstetrical history or the presence of known risk factors. Preconception intervention can be helpful in selected patients in a number of ways. Patients with certain uterine anomalies may have a surgical correction (i.e. removal of a uterine septum), and those with certain medical problems can be helped by optimizing medical prior to conception, be it for asthma, diabetes, hypertension and others.

During pregnancyReducing indicated preterm birthA number of agents have been studies for secondary prevention of indicated preterm birth. Trials using low-dose aspirin, fish oil, vitamin C and E, and calcium to reduce preeclampsia demonstrated some reduction in preterm birth only when low-aspirin was used.[34] Interestingly, even if agents such as calcium or antioxidants were able to reduce preeclampsia, a resulting decrease in preterm birth was not observed.[34] Reducing spontaneous preterm birthReduction in maternal activity pelvic rest, limited work, bed rest is frequently recommended although there is no clear proof of its efficacy. Also, increasing medical care by more frequent visits and more education has not shown a reduction in preterm birth rates.[46] Use of nutritional supplements such as omega-3 polyunsaturated fatty acids is based on the observation that populations who have a high intake of such agents are at low risk for preterm birth, presumably as these agents inhibit production of proinflammatory cytokines. A randomized trial showed a significant decline in preterm birth rates,[47] and further studies are in the making.

AntibioticsStudies examining the use of antibiotics have provided mixed results; a Cochrane review of 15 trials shows no major benefit,[48] in contrast a review by Lamont suggested that treatment of bacterial vaginosis if initiated prior to 20 w gestation is beneficial.[49] It has been suggested that the presence of a chronic chorioamnionitis may not be amenable to antibiotics, thus the difficulty to demonstrate their effectiveness.[34][edit] ProgesteroneProgesterone, often given in the form of 17-hydroxyprogesterone caproate, relaxes the uterine musculature, maintains cervical length, and has anti-inflammatory properties, and thus exerts activities expected to be beneficial in reducing preterm birth. Two meta-analyses demonstrated a deduction in the risk of preterm birth in women with recurrent preterm birth by 40-55%.[50]

HYPERLINK "http://en.wikipedia.org/wiki/" \l "cite_note-50" [51] However, progesterone is not effective in all populations, as a study involving twin gestations failed to see any benefit.[52]Cervical cerclageIn preparation for childbirth, the woman's cervix shortens. Preterm cervical shortening is linked to preterm birth and can be detected by ultrasonography. Cervical cerclage is a surgical intervention that places a suture around the cervix to prevent its shortening and widening. Numerous studies have been performed to assess the value of cervical cerclage and the procedure appears helpful primarily for women with a short cervix and a history of preterm birth.[53] Instead of a prophylactic cerclage, women at risk can be monitored during pregnancy by sonography, and when shortening of the cervix is observed, the cerclage can be performed. Women with a short cervix but no history of preterm birth, and women with twin gestation, do not benefit from a cerclage.[34]Tertiary (preterm birth imminent)Tertiary interventions are aimed at women who are about to go into preterm labor, or rupture the membranes or bleed preterm. The use of the fibronectin test and ultrasonography improves the diagnostic accuracy and reduces false-positive diagnosis. While treatments to arrest early labor where there is progressive cervical dilatation and effacement will not be effective to gain sufficient time to allow the fetus to grow and mature further, it may defer delivery sufficiently to allow the mother to be brought to a specialized center that is equipped and staffed to handle preterm deliveries.[54] Centers for the care of women with preterm delivery are usually staffed by maternal-fetal specialists and highly trained staff and linked to neonatal intensive care units (vi). In a hospital setting women are hydrated via intravenous infusion as dehydration can lead to premature uterine contractions.

GlucocorticosteroidsSeverely premature infants may have underdeveloped lungs, because they are not yet producing their own surfactant. This can lead directly to respiratory distress syndrome, also called hyaline membrane disease, in the neonate. To try to reduce the risk of this outcome, pregnant mothers with threatened premature delivery prior to 34 weeks are often administered at least one course of glucocorticoids, a steroid that crosses the placental barrier and stimulates growth in the lungs of the fetus. Typical glucocorticoids that would be administered in this context are betamethasone or dexamethasone, often when the fetus has reached viability at 23 weeks. In cases where premature birth is imminent, a second "rescue" course of steroids may be administered 12 to 24 hours before the anticipated birth. There is no research consensus on the efficacy and side-effects of a second course of steroids, but the consequences of RDS are so severe that a second course is often viewed as worth the risk. Beside reducing respiratory distress, other neonatal complication are reduced by the use of glucocorticosteroids, namely intraventricular haemorrhage, necrotising enterocolitis, and patent ductus arteriosus.[55]Despite being used for over 50 years to treat respiratory distress syndrome, glucocorticosteroid therapy is still controversial. Much of this concern is based on when these steroids should be administered (i.e. prenatally or postnatally) or for how long (i.e. acutely or chronically). For instance, recent clinical research has shown that the postnatal administration of dexamethasone can lead to permanent neuromotor and cognitive deficits.[56] This has led to a drastic reduction in the postnatal use of glucocorticosteroids in prematurely born infants. In addition, a recent large scale study has found that a second rescue dose of betamethasone prenatally does not improve preterm birth outcomes and leads to decreased weight, length, and head circumference.[57] Finally, while glucocorticosteroid exposure in the adult is considered safe, recent animal research has shown that a single exposure to these same drugs during brain development causes rapid brain degeneration.[58]

HYPERLINK "http://en.wikipedia.org/wiki/" \l "cite_note-58" [59] Despite these concerns, there is a consensus that the benefits of a single regimen of prenatal glucocorticosteroids vastly outweigh the potential risks.[60]The routine administration of antibiotics to all women with threatened preterm labor reduces the risk of the baby to get infected with group B streptococcus and has been shown to reduce related mortality rates.[61]Research reported at the 2008 conference of the Society for Maternal-Fetal Medicine suggests that administration of magnesium sulfate (Epsom salt) to women just before premature birth can cut the rate of cerebral palsy in half. While the compound is cheap and safe, it may make mothers and infants groggy, and details are pending scientific publication.[39][edit] TocolysisAnti-contraction medications (tocolytics), such as 2-agonist drugs (ritodrine, terbutaline, fenoterol), calcium-channel blockers nifedipine and oxytocin antagonists (atosiban) appear only to have a temporary effect in delaying delivery. Tocolysis has not fulfilled its promise as it is rarely successful beyond 24-48 hours because current medication do not alter the fundamentals of labor activation.[6] However, just gaining 48 hours is sufficient to allow the pregnant women to be transferred to a center specialized for management of preterm deliveries and give administered corticosteroids the possibility to reduce neonatal organ immaturity. Meta-analyses indicate that calcium-channel blockers and an oxytocin antagonist can delay delivery by 2-7 days, and 2-agonist drugs delay by 48 hours but carry more side effects.[34] Meta-analyses of magnesium sulfate failed to support it as a tocolytic agent.[6]When membranes rupture prematurely, obstetrical management looks for development of labor and signs of infection. Administration of corticosteroids is indicated prior to 34 weeks gestation. Prophylactic antibiotic administration has been shown to prolong pregnancy and reduced neonatal morbidity.[62] Because of concern about necrotizing enterocolitis, amoxicillin or erythromycin has been recommended, but not amoxycillin + clavulanic acid.[62]The routine use of cesarean section for early delivery of infants expected to have very low birth weight is controversial,[34] and a decision concerning the route and time of delivery probably needs to be made on a case by case basis.

The preterm babyMortality and morbidityThe shorter the term of pregnancy, the greater the risks of mortality and morbidity for the baby primarily due to the related prematurity. Preterm-premature babies ("preemies" or "premies") have an increased risk of death in the first year of life (infant mortality), with most of that occurring in the first month of life (neonatal mortality). Worldwide, prematurity accounts for 10% of neonatal mortality, or around 500,000 deaths per year.[63] In the U.S. where many infections and other causes of neonatal death have been markedly reduced, prematurity is the leading cause of neonatal mortality at 25%.[64] Prematurely born infants are also at greater risk for having subsequent serious chronic health problems as discussed below.

The earliest gestational age at which the infant has at least a 50% chance of survival is referred to as the limit of viability. As NICU care has improved over the last 40 years, viability has reduced to approximately 24 weeks,[65]

HYPERLINK "http://en.wikipedia.org/wiki/" \l "cite_note-pmid18240080-65" [66] although rare survivors have been documented as early as 21 weeks.[2] This date is controversial as gestation in this case was measured from the date of conception rather than the date of her mother's last menstrual period gestation appear 2 weeks less than if calculated by the more common method.[67] As risk of brain damage and developmental delay is significant at that threshold even if the infant survives, there are ethical controversies over the aggressiveness of the care rendered to such infants. The limit of viability has also become a factor in the abortion debate.

[edit] Specific risks for the preterm neonatePreterm infants usually show physical signs of prematurity in reverse proportion to the gestational age. As a result they are at risk for numerous medical problems affecting different organ systems.

Neurological problems include apnea of prematurity, hypoxic-ischemic encephalopathy (HIE), intracranial hemorrhage, retinopathy of prematurity (ROP), developmental disability, and cerebral palsy.

Cardiovascular complications may arise from the failure of the ductus arteriosus to close after birth: patent ductus arteriosus (PDA).

Respiratory problems are common, specifically the respiratory distress syndrome (RDS or IRDS) (previously called hyaline membrane disease). Another problem can be chronic lung disease (previously called bronchopulmonary dysplasia or BPD).

Gastrointestinal and metabolic issues can arise from hypoglycemia, feeding difficulties, rickets of prematurity, hypocalcemia, inguinal hernia, and necrotizing enterocolitis (NEC).

Hematologic complications include anemia of prematurity, thrombocytopenia, and hyperbilirubinemia (jaundice) that can lead to kernicterus.

Infectious include sepsis, pneumonia, and urinary tract infection [3]

A new mother holds her premature baby at Kapiolani Medical Center NICU in Honolulu, Hawaii

[edit] Neonatal careIn developed countries premature infants are usually cared for in a neonatal intensive care unit (NICU). The physicians who specialize in the care of very sick or premature babies are known as neonatologists. In the NICU, premature babies are kept under radiant warmers or in incubators (also called isolettes), which are bassinets enclosed in plastic with climate control equipment designed to keep them warm and limit their exposure to germs. Modern neonatal intensive care involves sophisticated measurement of temperature, respiration, cardiac function, oxygenation, and brain activity. Treatments may include fluids and nutrition through intravenous catheters, oxygen supplementation, mechanical ventilation support, and medications. In developing countries where advanced equipment and even electricity may not be available or reliable, simple measures such as kangaroo care (skin to skin warming), encouraging breastfeeding, and basic infection control measures can significantly reduce preterm morbidity and mortality.

Long term sequelaeMost children even if born very preterm adjust very well during childhood and adolescence.[68] As survival has improved, the focus of interventions directed at the newborn has shifted to reduce long-term disabilities, particularly those related to brain injury.[68] Some of the complications related to prematurity may not be apparent until years after the birth. A long-term study demonstrated that the risks of medical and social disabilities extend into adulthood and are higher with decreasing gestational age at birth and include cerebral palsy, mental retardation, disorders of psychological development, behavior, and emotion, disabilities of vision and hearing, and epilepsy.[69] Also it was shown that higher levels of education were less likely to be obtained with decreasing gestational age at birth.[69] People born prematurely may be more susceptible to developing depression as teenagers.[70] Some of these problems can be described as being within the executive domain and have been speculated to arise due to decreased myelinization of the frontal lobes.[71] Throughout life they are more likely to require services provided by physical therapists, occupational therapists, or speech therapists. Further long-term studies are needed to get a better picture about the sequalae of preterm birth.[68]Notable preterm birthsJames Elgin Gill (born on 20 May 1987 in Ottawa, Canada) was the earliest premature baby in the world. He was 128 days premature (21 weeks and 5 days gestation) and weighed 1 pound 6 ounces (624 g). He survived and is quite healthy.[72]

HYPERLINK "http://en.wikipedia.org/wiki/" \l "cite_note-titleMiracle_child-72" [73]Amillia Taylor is also often cited as the most-premature baby.[74] She was born on 24 October 2006 in Miami, Florida, at 21 weeks and 6 days gestation.[75] This report has created some confusion her gestation was measured from the date of conception (through in-vitro fertilization) rather than the date of her mother's last menstrual period making her appear 2 weeks younger than if gestation was calculated by the more common method.[70] At birth she was 9 inches (23 cm) long and weighed 10 ounces (283 grams).[74] She suffered digestive and respiratory problems, together with a brain hemorrhage. She was discharged from the Baptist Children's Hospital on 20 February 2007.[74]The record for the smallest premature baby to survive was held for some time by Madeline Mann, who was born at 26 weeks weighing 9.9 oz (280 g) and 9.5 inches (24 cm) long.[76] This record was broken in September 2004 by Rumaisa Rahman, who was born in the same hospital[77] at 25 weeks gestation. At birth she was eight inches (20cm) long and weighed 244 grams (8.6 ounces). Her twin sister was also a small baby, weighing 563 grams (1 pound 4 ounces) at birth. During pregnancy their mother had suffered from pre-eclampsia, which causes dangerously high blood pressure putting the baby into distress and requiring birth by caesarean section. The larger twin left the hospital at the end of December, while the smaller remained there until 10 February 2005 by which time her weight had increased to 1.18kg (2 pounds 10 ounces).[78] Generally healthy, the twins had to undergo laser eye surgery to correct visual problems, a common occurrence among premature babies.

Historical figures who were born prematurely include Johannes Kepler (born in 1571 at 7 months gestation), Isaac Newton (born in 1643, small enough to fit into a quart mug, according to his mother), Winston Churchill (born in 1874 at 7 months gestation), and Anna Pavlova (born in 1885 at 7 months gestation).[79]Summary

Description

Premature labor is defined clinically as progressive cervical dilatation and/or effacement with regular uterine contractions before the completion of 37 weeks of gestation

Spontaneous premature labor is the leading cause of preterm delivery

In most cases premature labor will result in preterm birth

Approx. 1 in 10 births in the US are premature

In some cases it will be appropriate to try to delay delivery with the use of tocolytic drugs

Urgent action

Arrange urgent admission (using an ambulance if necessary) to delivery suite for women in advanced labor.

Key points

10% of births in US are preterm

These preterm births account for an enormous cost to the healthcare system and society in general

Despite our best efforts little impact has been made in the prevention of preterm birth

The main role of tocolysis is to allow fetal exposure to steroids to enhance fetal lung maturity

Background

Cardinal features

Premature labor is defined clinically as progressive cervical dilatation and/or