POST TERM PREGNANCY

Dr. M.C.Bansal

Definition:

The average duration of pregnancy is 280 days(40 wks), If this period is exceeded by 14 days(2 wks), it is referred to as post term or prolonged pregnancy.

Incidence: 5-10% of all pregnancies.

Causes:

The commonest cause is error in calculation of gestational age.

History of post term delivery in previous pregnancy is the most most significant risk factor.

Congenital anomalies like anencephaly which disrupt foetal pitutary adrenal axis and rare maternal enzyme deficiencie(placental sulphatase.

In most cases cause is not known.

Complications:

A. Maternal: The placental function declines some time

around term. This exposes fetus to a state of relative hypoxia which can affect the fetal growth and the biophysical parameters of fetal well being.

In pregnancies where placenta continues to function well beyond due date, fetus continues to grow almost at the same rate as in third trimester.

Maternal complications arise from these two situations.

Maternal risks:

Increased maternal morbidity with large for date or macrosomic babies occurs because of increased incidence of:• Dystocia• Prolonged labour• Shoulder dystocia

This results in an increased risk of:• pelvic floor trauma• Instrumental

deliveries• Caesarian section

(25% incidence)

Maternal risks cont.

Fetal hypoxia and decreased liquor are associated with increased incidence of:• M

econium stained liquor• A

bnormal fetal heart rate patterns during labour

Increased operative deliveries

Increased risk of:• P

ost partum hemorrhage

• Endometritis

B. Fetal risks

Still birth rate increases significantly at term with advancing gestation.

It is 0.35/1000 pregnancies at 37 weeks While 2.12/1000 pregnancies at 43 weeks.

Perinatal complications which occur more frequently in post term babies are:

Meconium aspiration Asphyxia before, during and after delivery Cord complications Fractures Peripheral nerve injury Pneumonia Septicaemia Intra cranial hemorrhage

Prevention:

Recording LMP and calculating EDD at the time of first ANC visit.

Routine early ultrasound for dating of pregnancy. Review of antenatal card and ultra sonographic

reports in terms of fetal growth. Sweeping of membranes from 38 wks onwards

decreases number of pregnancies going beyond 41 and 42 wks.

Breast and nipple stimulation ? As soon as prematurity is ruled out in high risk

cases induction of labour will prevent post maturity.

Conditions where Post datism is not allowed:

1. PIH and eclampsia2. Rh incompatability3. Pregnancy with jaundice4. Previous 2 LSCS5. Transverse lie6. Contracted pelvis7. Precious baby8. IUGR9. PROM10. Previous history of IUFD11. Bad obstetric history12. History of APH/ Threatened abortion.

Management:

(A). Assessment of gestational age: gestational age must be confirmed to avoid unnecessary intervention for presumed postmaturity.

Calulation of expected date based on first day of last menstrual period.

A record of bimanual examination in the first trimester or fundal height in the second trimester.

Ultrasound dating in the first half of pregnancy- much more reliable than the last menstrual period.

(B). Induction versus expectant management:

The risk of uteroplacental insufficiency and still birth increases gradually at term, and termination of pregnancy is one of the methods to obviate this tragedy.

Perinatal and neonatal mortality increases significantly in pregnancies that continue beyond 41 wks.

The policy of routine induction of labour at 41 wks has reported reduced caesarian section rate and perinatal mortality.

(C). Role of fetal surveillance: Monitoring is most commonly done by:

Fetal kick count Non stress test Biophysical profile

Delivery is recommended if there is evidence of fetal compromise or oligohydramnios

(D). Management of unfavourable cervix:

Induction of labour in post dated pregnancies with unripe cervix may increase the incidence of failed induction, operative deliveries and caesarian section.

Prostaglandins are now used as the first choice whenever cervical ripening is required in nulliparas or multiparas.

Misoprostol is not prefered in women with previous uterine scar because of increased risk of scar dehiscence. Misoprost also causes sudden decrease in foetal heart activity leading to IUFD.

Electronic fetal heart monitoring must be used when prostaglandins are administered because of risk of hyperstimulation.

INTRAUTERINE FETAL DEATH

(IUFD)

Definition:

Foetal Death prior to the complete expulsion or extraction from its mother’s womb irrespective of the duration of pregnancy. Foetal Death is indicated by the fact that after such expulsion or extraction, fetus doesn’t breathe or show any other evidence of life such as: -Beating of heart -Pulsations of umblical cord -Definite movement of voluntary muscles

Heart beats must be distinguished from transient cardiac contractions; and respiration from fleeting resp. efforts and gasps.

Definition contn.

For statistical purposes it is recommended by WHO that Intrauterine death occuring after 20 wks or fetal wt >500g when gestational age is not known, should be classified as fetal death, to differentiate from early pregnancy loss or spontaneous abortion. This is further subdivided into:

Early fetal death(20-27 wks) Late fetal death(>= 28 wks)

Incidence: 6.9 per thousand births. (U.S.)

Aetiology:

Risk factors associated with still births can be: Maternal Fetal Obstetric complications Medical disorders complicating pregnancy

Maternal factors:

Advance maternal age (>35yrs)-increases risk of diabetes, hypertension, congenital anomalies etc

Obesity- increases risk of diabetes, hypertension, placental dysfunction

Race- black women have higher still birth rate

Low Socioeconomic status Low educational status Smoking, tobacco and drug abuses

Fetal factors:

Congenital malformations: e.g. anancephaly not associated with polyhydramnios

Male sex: chromosomally poor survival rate as compared to female foetus

Obstetric complications:

IUGR PIH Placental abruption Rh isoimmunisation Multiple pregnancy Post term pregnancy Infections Antepartum asphyxia Previous history of stillbirth Nuchal cord or knotted cord( true knots)

Infections:

In utero viral, bacterial and protozoal infections have been asociated with adverse pregnancy outcomes like preterm labour, PROM, unexplained still births.

Viruses most commonly incriminated are- parvovirus B19, CMV.

Bacterial infections which contribute to increased risk are listeria monocytogenes, E.coli, group B-streptococci, ureaplasma urealyticum, syphilis.

Still births due to infections usually occur in fetuses weighing <1000g.

Medical disorders

Diabetes Hypertension Chronic nephritis SLE Thrombophilias Cholestasis of pregnancy

Thrombophilias

Thrombophilias (both inherited and acquired) because of their increased tendency for vascular thrombosis, may cause thrombotic lesions in the placenta causing: recurrent miscarriages Pre-eclamsia IUGR Still births

Diagnosis:

Clinically: IUFD is suspected when- The mother reports loss of fetal movements. Fundal height on palpation is less for

estimated gestational age or fundal height regresses as compared to previous documentation.

Absence of fetal heart sounds on auscultation or doppler.

Ultrasonography: confirms the diagnosis by noting absence of fetal heart activity.

Management:

1. Counseling regarding the probable cause of death, need for investigations and autopsy of infant after death, options available for further management should be sympathetic and unhurried.

2. Termination of labour: Spontaneous labour usually ensues after

intrauterine death in 80-90% cases within 2 wks. In those that do not go in labour there is a risk of

hypofibrinogenemia and consumptive coagulopathy(25%). It doesn’t usually occur prior to 3-4 wks of retension of the dead fetus. Infection is a risk if membranes are ruptured.

Induction of labour: Oxytocin infusion in titrating doses Prostaglandins: PGE2, PGF2-alpha,

misoprostol. Mefipristone (RU 486) -an anti progesterone Trans cervical extra-amniotic Emcredil

instillation.

Evaluation

A thorough evaluation must be undertaken in every case to identify the likely cause of still birth which will help in counselling the patient regarding the need for prenatal diagnosis and preconception management in future pregnancies.

About one-fourth of fetal deaths remain unexplained despite adequate evaluation.

Evaluation includes:

1. Detailed history: Relevent maternal and obstetric factors must be

reviewed. Family history particularly of pregnancy losses,

congenital malformations, consanguinity, mental retardation and diabetes.

2. Laboratory and cytogenetic evaluation: Amniocentesis: for cytogenetic diagnosis Bacterial culture TORCH serology Fasting or random blood glucose level HBA1c VDRL Antiphospholipid antibodies

Evaluation cont.

3. Post Partum examination: After delivery, the newborn and placenta must be examined by an experienced person. Placenta should be sent for gross and microscopic examination. Culture for bacteria and viruses should be done. Permission must be obtained for clinical photographs, X-rays and autopsy.The time of death may be approximately determined by examination of the infant and assessing degree of maceraton:

Time of fetal death and grade of maceration:

Grade of maceration:

features Time since fetal death

0 “Parboiled” reddened skin

<8hrs

1 Skin slippage and peeling

>8hrs

2 Extensive skin peeling; red serous effusions in

chest and abdomen

2-7 days

3 Liver yellow-brown; turbid effusion

>=8 days

Conclusion:

Intrauterine death is a tragedy which should be prevented as far as possible. Nevertheless it occurs despite best intensions, a thorough search must be undertaken to identify the cause so that repeated mishaps can be effectively averted.