Fetal Development

Jessica Walker

First Trimester

Week 1 & 2 Your last menstrual cycle has just ended and your body is getting ready for ovulation. Ovulation normally take place 11-21 days from the first day of you

last period. During intercourse, there are several hundred million sperms that are released into the vagina. The sperm will travel through the cervix and into the fallopian tubes. When conception take place, the sperm in put through the an

egg and creates a single set of 46 chromosomes called a zygote. The egg spends a

couple of days traveling through the fallopian tube toward the uterus, which is

dividing into cells called a morula. The morula soon becomes the blastocyst and it

eventually ends up in the uterus. Anywhere from 6-12 days after conception , the blastocyst

will implant itself in to the uterine lining and begin the embryonic stage.

Week 3While you may still no you are pregnant the embryo is going through lots of

basic growth at this time, with the beginning development of the brain, spinal cord,

heart, and gastrointestinal tract.

Week 4Your fetus is now the size of a apple seed. Now you may begin to have signs that you are pregnant. By the end of week four you will have missed your period. Other signs of pregnancy may include: o Nausea and vomitingo Breast tenderness and darkening of the areolaso Excessive salivationo The need to urinate more frequentlyo   Skin changes, including breakoutso High basal temperature, a temp over the cover line for 18 days in a rowo Fatigueo A missed periodAt this point your embryo has three main brain sections: forebrain, middle brain, and hindbrain. Some parts of the eyes are becoming visible (pigment and optical stalk). The mouth and the tongue are now coming clearer as well as the thyroid and Lymphatic system is forming. Also, the lung buds are forming and the heart is quite large. The first thin layer of skin is formed and buds that will become arms and legs are becoming visible.

Week 5 At this point your baby is beginning to define a shape. The placenta and the

umbilical cord is what is providing nourishment to your baby. The first system to form is the circulatory system and it is functioning with all four parts of the heart. Your ultrasound will now show the first sing of a heart beat. Depressions in the face are now forming and the eyes, ears, mouth and nose will become more distinct and the small crease beneath will become the neck and lower jaw.  The arms and legs are becoming more shaped and can be notable. The fingers are now beginning to grow.  A footplate is beginning to grow on the bottom of the legs.  At this point your emotions may be affecting you and your hormones may have you feeling a little out of whack. Some may just now be finding out they are pregnant but others many have had an pelvic exam and possibly a ultrasound

Week 6During your 6th week your baby will grow to ¼ of an inch. Your embryo looks a lot like a tadpole at this time. Half way through this week your baby will have it`s first movement but you are unable to feel it because you are not in your second trimester. Your amniotic sac has entirely formed and the baby is moving around in this sac. The nostrils are beginning to form and the neural tube that connects the brain and the spinal cord will close this week. Also, the skeleton is formed, the appendix are placed, and the intestines are developing. At this time the brain hemispheres have formed and brain waves can be recorded. Now the heart has four different chambers and the heartbeat will become more regular. Next, cluster of cells that will become the reproductive organs has formed. Note to Women: You may notice that your close are fitting tighter, Also, certain foods you may be sensitive to, so try to avoid them to prevent morning sickness.

Week 7Your embryo is now about ½ and inch long this week. The head is very outsized for all of the facial features that are becoming more obvious. The eyes are now formed but won`t open until the 28th week and the eyelids are beginning to form. Your babies indentations and the semicircular canal is beginning to form in the inner ear to help with balance. Also, the brain is close to completion and is growing at an amazingly fast rate. The buds that are arms and legs are now noticeable. At this point the development of the arms will end and the hands will continue to grow over the next few days. Now the critical development of the legs will end soon, but the knees and ankles can be distinguished by small dots on the legs and the toes are notched and toenails are beginning to appear. At this time you can’t tell the difference from boys and girls yet by sight, but the gonads are formed.  The gonads are either the testes in the male, or the ovaries in the female. The heart is beating at around 150 beats per minute, about twice your heart rate, and will continue to do so throughout your pregnancy.  The kidneys produce urine for the first time.  Your baby will rapidly go through three sets of kidneys, the second set will form this week.  When bone marrow will form later and it will take over the production of red blood cells, but for now the liver is working over time to produce these

Week 8Your baby is no longer called an embryo and is now called a fetus. The fetus is now the size of a grape and has doubled in it`s size in the last two weeks. The body parts that have formed up until this point will now begin to become more particular.  This is a very busy developmental period that will last for about 20 weeks.  Right now the fetus is developing teeth and it`s palate. The ears are continuing to develop but right now they are located low on the head and will move up as the head grows. The skin is very thin and the veins are clearly visible. The fingers and toes are forming now and the arms can flex at the wrists and elbows.  Also, the bones for the arms and legs are beginning to harden and joints are forming.  The head has now grown quite fast and is still very large compared to the rest of the body. The hindbrain, which is responsible for the breathing. Heart regulation and muscle movement is now forming. Now the critical period of the heart development is ending and the heart will continue to develop but at a much slower pace. Blood has begun to flow through a basic circulatory system and the tubes from the throat to the lungs are now formed. Finally, the intestines are beginning to develop within the umbilical cord.  When the body is large enough, they will move into the proper area.  Your fetus still has a tail, but it is smaller than in the past, and its entire body is straightening out. 

Week 9Now, you uterus has grown to about the size of a grapefruit to accommodate

your baby. Your baby is about 1 inch long and weighs about 4 grams. This week the

tail disappears and the organs. muscles and nerves are beginning to function. The

babies eyelids are beginning to cover the eyes and your baby is beginning to look

more and more like a human. They can suck their thumb already and make all kinds of

facial movements. These facial movements include frowning, swallowing motions

and moving the tongue around. The placenta is now nourishing the baby.

Week 10Your baby is now about 1 ½ inches long and weighs about 5 grams, it

resembles the shape and size of a peapod. Your hormones are going crazy and you might be

sad one minute and happy the next. Being very emotional is normal and it will even

out over the next few weeks. Although, the sex of the baby cannot be seen by an

ultrasound the genitals are forming. Also your babies brain is forming 250,000 neurons

every minute and brain development is very rapid at time. Your babies head is

upright and your baby can turn their head, open their mouth, smile and practice breathing.

Now the outer ear is completely formed and the inter ear is almost complete. The intestines begin moving from the umbilical cord to the abdomen and all the

vital organs are formed and starting to work together and the lungs are continuing

to develop. The arms and legs are well formed and fingers and toes are not

webbed any longer.  All of your baby’s joints are formed, so they can bend their fingers and make a fist.  The can kick and curl up their toes.

Week 11At this point your baby is about the size of a lipstick tube at this point; weighing in at about 9 grams and measuring around 2 inches long. With a dopler you should be able to hear the babies heartbeat now. All of the critical development is done at this point, now all that needs to happen is for your baby to grow. Right now your babies head is half of it`s length and the forehead bulges and sits very high on the head. On an ultrasound you would be able to see the clear outline of the spine. The reproductive organs develop very rapidly this week.  The external genitals are developing into either a penis or a clitoris and labia majora.  By the end of the week these external genitals are recognizable and it should be easier to see if parents are having a boy or a girl. All of the vital organs are functioning by the end of the week. Kidneys are producing urine and the pancreas is producing insulin.  At this point, only growing and becoming more efficient is left to do.

Week 12This week your baby weighs about ½ an ounce and is about 3 inches long. If you could see your baby right now you would observe that your child is very active. Your baby is kicking, twisting, and turning. The baby is completely engulfed in amniotic fluid at this point.  This fluid is about 1.5 ounces in volume. The growth of the baby’s head slows down considerably by the end of this week.  The brain has the same structure it will have at birth, although it will be quite larger.  Hair is beginning to grow on the baby’s head now and teeth are forming as well as taste buds and vocal cords. The intestines are beginning to contract as if they were digesting food and are moving from the umbilical cord into the body cavity.  A large portion of the amniotic fluid will be the baby’s urine from this point on as the kidneys begin to excrete urine. If this is your first pregnancy. you probably aren’t showing yet, although your clothing and bra is probably feeling very snug.  If this is not your first pregnancy your abdominal muscles are not as strong and you may be starting to show.  You might want to invest in some looser clothing, although you may not be quite ready for maternity clothes just yet. 

Week 13As you near the end of the first trimester, your baby is almost 3 inches long

and weighs about ½ an ounce.  At this point you are probably ready for looser fitting clothing, soon you won’t fit into your regular clothes at all. The baby’s face is looking more and more human.  The eyes have moved closer together and the ears are near their normal position on the side of the head.  The head now rests on it’s neck as opposed to the shoulders and is still roughly half the entire length of the body. Right now, your baby’s heart is pumping about 25 quarts of blood each day.  At birth about 300 quarts of blood per day are pumped.  The liver is making bile and is supervising the activity of the fully working spleen.  The spleen removes old red blood cells and produces antibodies.  Your baby is able to absorb sugar, or glucose, at this point. Your health practitioner can feel the top of your uterus, or fundus, when they push on your abdomen.  You haven’t reached the advanced stages of pregnancy yet, so you are probably still pretty comfortable and many of the early pregnancy symptoms (such as morning sickness) should begin to diminish at this point.  At this point in your pregnancy the risk of miscarriage greatly decreases.

Second Trimester

Week 14As you begin your second trimester your little weighs in at a little over an ounce and at 3 ½ inches – about half of a banana.  Impressive as the growth ha s been in the last few weeks, in the next four weeks your baby will grow to nearly a pound in weight!  The body will finally start to catch up with the head and be more proportionate.  If you poke at your abdomen and the baby feels it, it will begin to root around as if looking to suckle.  Their little face starts to resemble Mom and Dad as they continue to develop more normal looking facial features.  Baby can hear sounds now and are able to feel pain.  They have hair and eyebrows beginning to grow, as well as Lanugo – the fine hairs that cover the baby’s body and protect the skin.  The baby now has unique fingerprints. Inhaling and exhaling movements have begun and the torso is growing very quickly to make up the difference in body and head size.  All nourishment is received through the placenta.  The intestines continue their migration into the body from the umbilical cord. At this point you may begin to feel “quickening”: a fluttering sensation in your abdomen.  This is actually your baby moving around!  It might be several weeks before you notice it, but some Mom’s notice this as early as 14 weeks. 

Week 15Your baby now weighs in at about 1 ¾ ounces and is about 4 inches long.  Finally the growth of the body is catching up with the head so that they the baby doesn’t look so top heavy.  The hair follicles begin to make pigment for dark haired babies and their bodies are completely covered with lanugo, fine hairs that protect the skin.  These hairs will disappear before birth, usually.  Hearing is becoming more sensitive and if you play music or sing your baby can hear it.  Loud noises can

startle the baby at this point in time.  The heart is still pumping away, practicing for the larger volume of blood it will pump when born.  Babies are practicing inhaling and exhaling movements.  Fingernails are completely produced and the legs are getting longer than the arms.  The skeleton is getting harder and taking in calcium quickly.  Muscles are developing, as is the very thin skin.

Week 16Your baby is now about 4 ½ inches long and weighs about 51/2 ounces.  Hard to believe when you consider that most women have gained somewhere between 5 and 10 pounds!  Just remember, your weight gain includes a lot more than just the weight of the baby, including the placenta, amniotic fluid and a larger volume of blood. Your baby now gets the hiccups, but since they have fluid instead of air in the trachea they don’t make any sound.  They also like to play, by pulling and tugging and squeezing on the umbilical cord. The baby’s legs are beginning to grow longer than the arms now and the movement of all of the baby’s limbs is becoming more coordinated.  The eyes have reached their final destination on the head and are no longer on the sides of the face.  The baby is urinating about every 40-45 minutes and Meconium – the first stool the baby produces is beginning to collect in the bowels. 

Week 17About the size of an avocado now, your baby weighs about 6 ounces and is about 5 inches long.  Over the next few weeks your baby is about to make a huge jump in size, nearly doubling their weight and getting much longer as well.  This will help them to be more proportionate in size, letting the body catch up with the head. Now the eyes are in the final position and the ears are just about done moving as well.  Permanent teeth buds are forming behind the baby teeth buds that are already in place.  The baby’s heartbeat can be clearly heard in the doctor’s office with special equipment. Baby’s bones are becoming harder and a special substance, called Myelin, slowly forms a protective barrier for the spinal cord.  Vernix, the protective sealant for baby’s skin is starting to form and cover the skin now, too. As your uterus begins to grow and make room for the baby you may begin to experience round ligament pain now.  This is normal and should subside with rest.  Round ligament pain is felt on the sides of your abdomen.  If the pain is severe or does not subside with rest you should talk with your health practioner.

Week 18Your baby is now about 5 ½ inches long and weighs about 6 ounces.  During this week the baby will gain weight at an incredible pace!  Now that all of the organs have developed the baby’s body will focus on gaining weight and size.  You may begin to feel a bit off center as the baby and your uterus is getting larger. Because the baby’s inner ear has formed its bones and nerve endings from the brain have formed, hearing has become very acute.  Your baby can hear your heartbeat and the blood moving through the umbilical cord as well as your voice.  They will even try to cover their ears if they hear a loud sound!  Baby becomes sensitive to light now, as the eyes are further developed and the brain is growing very fast.  A little girl will have all the eggs inside her ovaries that she will need for her entire life.  Little boys begin to develop the prostate gland.  Meconium, or the first bowel movement continues to accumulate inside the bowel.  Brown fat begins to cover the baby, so their skin appears less transparent.

Week 19Right now your baby is about 6 inches long and weighs about 7 ½ ounces.  If you haven’t felt baby move yet, hang in there, because baby is moving all around and soon you’ll recognize and feel those movements. Your baby’s brain is continuing to develop at an amazing rate.  Millions of motor neurons are forming inside the brain, this allows the baby to make voluntary muscle movements, including thumb sucking and moving away from lights.  The forebrain is dividing into two hemispheres that will become the two cerebral hemispheres of the brain.  The nerve cells that serve the senses are also developing quickly now. Your baby continues to mimic breathing, with their chest moving up and down taking in amniotic fluid to practice for their birth.  Reproductive organs will continue to grow and develop and can be distinguished on an ultrasound.  Be sure and tell your technician if you do not want to know the sex of your baby so that they won’t spoil your surprise!

Week 20Your baby now weighs about 9 ½ ounces and

measures about 6 ½ inches long.  You’re halfway through your pregnancy and baby is very active by now!  Over

the next few weeks the baby will move so much that it

may be hard to sleep.  This will continue until it gets very crowded for the baby.  Babies that are born at 20 weeks have a 50% chance of survival

Week 21Your baby is now about 10 ½ ounces and measures about 8 inches long – about the size of a large banana.  The rapid growth that has happened over the last few weeks will slow down now.  Every week increases the baby’s chance of survival outside of the womb now. The head is now about 1/3 of the size of the body now.  Rapid eye movements begin at twenty-one weeks and baby can hear when you talk or sing to them now.   Swallowing, which is believed to help baby’s digestive system function after birth, continues at this point.  The heart is growing stronger and can be heard when you visit the doctor’s office.  Fat continues to accumulate now and the bones and muscles are getting stronger each day. By now, most people can probably tell that you are pregnant.  Your body is changing rapidly as the baby grows.  Be sure to get plenty of rest and eat healthy.  Exercise is a great way to stay in shape and keep healthy.  Check with your health practitioner to find out what types of exercise would be appropriate for your pregnancy.

Week 22Your baby weighs about 13 ounces now and measures about 9 inches long.  They are very thin, but completely developed at this point!  Fat will continue to accumulate from here on out as your baby packs on the pounds getting ready for birth. The bones inside the ears are hardening and so their hearing becomes more clear.  They can distinguish between different sounds such as your voice and heartbeat.  Eyes are developed now, but there isn’t any pigment in the colored part.  Teeth buds appear beneath the gum line and the lips are completely developed and distinct from the rest of the face. Lungs are developing.  Right now, the lungs cannot transfer oxygen to the bloodstream, but by birth the lungs will be ready.  The senses continue to develop at this time and your baby may experiment with touch by stroking their own face.  White blood cells are forming now so that your baby can help fight illness and infections. The pancreas and liver are developing now.  The pancreas produces hormones and the liver breaks down bilirubin, a substance produced by red blood cells.  Hand strength is very good now and the skin is pink and wrinkly.  As the baby gains more weight the skin will become less transparent and wrinkled.

Week 23Your baby has now reached the 1-pound mark and measures about 11 inches Long.  You may be smaller or larger than other people that are 23 weeks pregnant, but what is important is that you have steady growth and that you are taking care of yourself. This week your baby’s nostrils will open and the enamel that will cover baby’s teeth is forming.  Surfactant, which is a substance that helps the lungs expand after birth, has begun to develop and the air sacs inside the lungs are growing. All the nerve cells are all in place now and will begin to join together to fully form a nervous system.  Baby is moving around a lot now, and you’re probably feeling the full force of their movements.  This daily movement helps them work out their developing muscles.  Keep eating a healthy diet, including calcium and iron.  Your baby’s bones are absorbing calcium as quickly as they can so they can be strong and healthy at birth.  Fat is continuing to accumulate, but the skin still appears very wrinkly.  Once your baby has filled out a little the skin will appear less loose.

Week 24Your baby now weighs a little over a pound is about 11 inches long.  They fully fill

the uterus now, but there is still plenty of room for growth.  Over the next three months your baby will have the biggest weight gain. Brain waves are beginning to activate the auditory and visual systems, causing the baby’s mouth and lips to become sensitive.  Eyes will respond to light and the ears are reactive to sounds from outside of the uterus.  Your baby may be able to tell when they are upside down now because their inner ear is completely developed.  The brain is very active now and is regulating all other body functions.  Toenails and fingernails are growing now and may need trimmed when they are born.  Blood vessels in the lungs are developing and will exchange oxygen after birth.  The alveoli (the very tiny final branches of the respiratory tree) and air sacs have developed completely. You may start to get stretch marks now.  This is a normal part of pregnancy.  Your health practitioner may order a blood test now to check for anemia and infection.  You may also have a glucose screen between now and week twenty-eight to help rule out gestational diabetes.

Week 25Your baby is now about 1 ½ pounds and measures around 12 inches long.  You are closely approaching your third trimester and the final stretch of your pregnancy.  Now is a great time to investigate and start birthing classes if you haven’t already done so.  By now, people may be noticing that you are pregnant.  Maternity clothes may be a necessity, although you may still fit into

some of your pre-pregnancy, looser clothing. Taste buds are developing at this point and the baby even is able to distinguish sweet tastes.  Blood vessels are developing in the lungs to prepare for their vital function after birth, but for now they are filled will amniotic fluid and are practicing breathing movements.  Breathing is controlled by the nervous system. If you were to shine a flashlight on your abdomen, the baby will turn their head toward the light  because the optic nerve is now working.  Fingerprints, toenails and fingernails are fully formed and the spine is straightening out.  Bones are continuing to harden at this time.Vernix, the waxy substance that covers your baby, is forming at a rapid pace.  This protects their skin and helps regulate body temperature.

Week 26Your baby now weighs about 2 pounds and is about 13 inches long.  You’ve reached the end of your second trimester and now time may seem to crawl along as you wait through these final weeks.  Just remember that soon you will have a new little one to hold and love! This week the eyes are opening and beginning to blink.  Before now, the eyes have been sealed shut so that they can continue to develop the retina.  Baby’s eye color, depending on their coloring and ethnic background, may be dark or brown, or they could be grayish blue.  Depending on your baby their eyes may change colors during the first few months after birth.  Eyelashes are growing now, as is the hair on their head. Taste buds are continuing to develop and they are improving their sucking and swallowing motions.  Brain waves become stronger this week, which affects the vision and hearing.  The smooth brain is now forming grooves and valleys. The bronchial tract develops this week and the lungs are growing.  If your baby were born now, it would have an 85% chance of survival, but the lungs are still very immature.

Third Trimester

Week 27You’ve made it to the final trimester now, only 10 weeks to go!  Your baby now weighs about 2 pounds and is about 14 inches long.  They look like a fully formed baby at this point, only smaller and very thin.  Survival, if born now, is around the 85% chance rate.  Baby will go through another growth spurt now and may have predictable periods of sleep now. The ears are covered the waxy substance called vernix which may muffle the sounds that they hear.  Some experts believe that babies begin to dream at week 28, because the brain is so very active now.  Brain tissue is developing rapidly. It’s possible to hear the baby’s heartbeat by just placing an ear on your abdomen at this point!  Lungs have developed enough that they could function outside of the womb and the central nervous system is well formed. Amniotic fluid and the absence of fat on your baby’s body makes their skin appear wrinkly at this time.  Baby will continue to fill out after they are born and begin to gain newborn weight.

Week 28This week your baby weighs about 2 ½ pounds and measures around 15 inches long.  During the last four weeks the weight of your baby has nearly doubled.  The baby is moving around a lot these days, but soon this will slow down as the baby starts to run out of room inside your uterus. The smooth brain tissue continues to develop folds and wrinkles as it increases in mass.  Brain functions include breathing and maintaining body temperature.  Lanugo hair is starting to disappear over the body, but eyebrows, eyelashes and the hair on their head is growing.  Bone marrow has taken over the production of red blood cells from the liver at this point.  Muscle tone is improving and the baby’s body is filling out with warming body fat.  The third trimester is filled is aches and pains and general discomfort for many women.  Some of the complaints you might suffer from include heartburn, varicose veins, hemorrhoids and indigestion.  Knowing that you are closely approaching the birth of your baby can help you make it through these trying last few weeks.

Week 29This week your baby weighs in at 2.6 pounds and measures at about 16 inches.  To help with the discomforts of pregnancy that you may be having at this time you should get plenty of rest, wear comfortable, supportive shoes and continue to eat a healthy balanced diet.  If you haven’t started working on your birth plan, now is the time to get started!  Be sure to get your partner’s input on this important document that will help guide everyone during your labor and birth. Baby’s head is no longer disproportionate to the rest of the body.  The senses are functioning and the eyes can move around inside the eye sockets.  Little boy’s testicles are now moving toward their scrotum and little girls will have a prominent clitoris because it is not yet covered by the small labia, as this happens in the last few weeks of pregnancy. Baby’s skin is becoming less wrinkly as they continue to add fat and gain weight.  The uterus is becoming more cramped now and the kicks and punches that you have felt will probably feel less pronounced at this point.  You’ll definitely still be able to tell that baby is there, though!

Week 30Your baby now weighs about 3 pounds and measures 16.2 inches.  Things are started to get cramped inside the uterus at this point, and the baby is really in the fetal position – with knees bent and their chin touching the chest.  Soon baby will move into the head down position getting ready for their delivery. Babies do not usually have 20/20 vision when they are born.  Their eyes are well developed and they are reacting to light, but most children do not have 20/20 vision until they are between seven and nine years old.  The brain is continuing to grow and make connections between nerve cells.  Baby’s digestive tract is nearly complete now and the lungs are nearly fully developed as well.  Lanugo continues to disappear now and the hair on their little heads is coming in.  Some babies are born with a full head of hair! Sleeping on your left side is probably the most comfortable position for you now, as it will help remove some of the pressure on the nerves and blood vessels in your back.  It may seem as if everyone has a horror story to tell you now about her labor and birth.  Just remember that every birth is different and don’t feel shy about asking people to keep the stories to themselves if they bother you.  You might also find that complete strangers feel the need to touch your belly – everyone gets excited as the birth of your little one grows closer.

Week 31Your baby now weighs about 3.3 pounds and measures about 17 inches.  Growth will begin to slow down now, but the average weight of babies at birth is around 7 pounds.  Baby is opening and closing their eyes this week.  A brain scan would show that your baby is probably having dreams now.  Lungs are quickly developing now, getting ready for full time work after birth.  White fat is now being deposited beneath the skin, which helps make baby’s skin look pink. By now you should be

seeing your health practitioner every two weeks.  Your doctor or midwife will be checking your blood pressure and any swelling in your arms and legs, measuring the baby, asking you about how the baby is moving around and keeping close tabs on you and the baby in general.  They’ll start paying attention to what position the baby is in now, as the birth gets closer.  About 96% of babies born are born head first.  The rest are born breech with the buttocks or feet coming first.  Having a breech birth does not mean an automatic cesarean section, but be sure and talk with your doctor or midwife if you are concerned. It’s probably time for you to remove your rings, if you have not already done so, because with swelling it can become very hard to remove these later.

Week 32Your baby now weighs about 4 pounds and measures about 17 inches.  If you’re feeling kicks in your ribcage it probably means that baby has finally moved into the head down position that 96% of babies are born in.  Don’t worry if this hasn’t happened yet, you still have a few weeks left for baby to move. During baby’s awake times their eyes are open and looking around.  When they are sleeping their eyes are closed.  Eye color is usually blue right now, but this will change with exposure to light, and then it can change again a few months after birth. Little boys testicles are descending into the scrotum now.  Sometimes this doesn’t happen until after birth, but this condition usually corrects itself.  Baby’s immune system is starting to develop now and sometimes the fingernails are so long that they will scratch themselves.  White fat is continuing to accumulate now.  This helps baby’s skin appear more pink and diminishes the wrinkly appearance of your little one’s skin. If you haven’t already gotten a list together of the things you need to take with you to the hospital youshould start now.  Ask your health practitioner what signs to watch for to indicate you are in labor and when they would like for you to call their office.  Be sure and ask what the procedure for contacting them is once you think you are in labor.

Week 33Your baby now weighs about 4.4 pounds and measures about 17.8 inches.  Baby will gain one third to one half of their weight during the final weeks of your pregnancy.  The amniotic fluid is now at it’s highest level and will stay at this level until your delivery.  Your little one may have now settled into the head down position; however, some babies do not do this until later in pregnancy. The baby’s skull is not joined and is very pliable.  The brain is rapidly growing now and increasing in size.  Fat is rapidly accumulating and changing the color of your baby’s skin from red to pink, the skin appears less wrinkly as they continue to accumulate this white fat. Because your baby is rapidly gaining white fat and weight at this point you may be gaining weight more rapidly than in the past as well.  Continue to eat right and exercise as you can to help your baby grow and develop at a normal pace.  Now may be the time to decide if you will circumcise your little boy after his birth.  Continue to plan the details of your baby’s arrival including your birth plan the details of the nursery for when they come home.

Week 34Your baby now weighs about 4.9 pounds and measures about 18.4 inches long.  Your baby is fully developed at this point, but is growing and gaining weight now.  Baby’s chances of survival outside of the womb are very good now, with only the lungs needing further development. Baby is probably in the head down position now and the skull is soft so that baby can move down the birth canal during birth.  Pressure from the baby being head down can make you have to urinate frequently. The immune system is continuing to mature now and preparing to fight infections. Because your baby is rapidly building up fat, little dimples are forming at the elbows and knees.  Creases are forming around the wrists and neck.  Bones are continuing

to harden now and the waxy substance covering your baby’s skin, vernix, is thickening. There are several prenatal tests that your health practitioner may recommend at this point.  One that you need to ask for, if your doctor or midwife doesn’t suggest is, is the GBS (or Group B Step) test.  This test screens for harmful bacteria that you can pass to the baby at birth.

Week 35Your baby weighs about 5 ½ pounds now and measures about 18.9 inches long.  As you know each baby has a different weight and length at birth, so these measurements are just an average.  Now your baby will start it’s most rapid weight gain, adding ½ to ¾ of a pound every week until they are born. You may be able to distinguish body parts such as a head, hand or foot now that your baby is getting larger and your uterus is getting thinner.  Baby’s hearing has completely developed now and the lungs are very close to being complete and ready for birth.  The kidneys are fully developed and the liver is able to process waste products.  Fat is continues to accumulate at a rapid pace now, which will help your baby stay warm after they are born. When you visit your health practitioner now they may begin to exam your cervix to see how ready it is for delivery.  If you are not having a home birth, have your overnight bag packed and ready so that when your labor starts you have everything you want and need ready to go to the hospital or birthing center.

Week 36Your baby now weighs about 6 pounds and measures about 20.7 inches long.  You’ve almost made it to the end now.  Keep this in mind as you continue to grow increasingly uncomfortable.  Your health practitioner will probably want to see you weekly now. Fat is deposited in the baby’s cheeks this week and the muscles that help your baby suck are helping to fill out their little faces.  Your baby’s bones are very strong, but the skull is going to stay soft, so that it can pass through the birth canal. Baby’s immune system is continuing to develop and now they are receiving your antibodies.  Liver and kidneys are now fully developed and functional, allowing baby to process some of their own waste.  Meconium is accumulating rapidly now.  This first bowel movement is normally voided soon after birth, but some baby’s will void while they are still waiting to be born.  Your baby is now a plump, round little person.  All the extra weight and fat accumulation over the last few weeks has filled out their little bodies. If you haven’t already had a GBS, or Group B Strep test, now is the time to ask your doctor or midwife about this test.

Week 37Your baby now weighs about 6 ½ pounds and measures about 21 inches long.  You are now considered a full term pregnancy, if you go into labor now, your health practitioner would not try to stop your labor! Baby is gaining lots of weight now, about ½ an ounce each day.  Typically, boys will weigh more than girls at birth.  Right now, your baby is practicing their breathing and getting stronger.  Every baby is different, but some are born with as much as 1 ½ inches of hair already grown.  You probably can’t wait to see your little one at this point, but you are very close to the end of your waiting.  Lungs are almost completely mature now; in a few days they will be done maturing.  Your baby is becoming more coordinated now and can grasp things with their little fingers. You may have a pelvic exam this week to see how your cervix is progressing.  Don’t forget to pack your bag and get together all the things you’ll need at the hospital or birthing center, including the camera and car seat. 

Week 38Your baby now weighs 6.8 pounds and measures about 21 inches long.  This is what many babies weigh when they are born, and your little one is just around the corner from arriving.  Baby is gaining about an ounce each day. Since your baby is using their lungs to practice breathing they may get hiccups occasionally and you will be able to notice these little jumps.  The head and abdomen are about the same circumference at this point.  The abdomen is large because of the liver, which is producing red blood cells.  Tear ducts will not appear until a few weeks after birth.  The brain and the lungs are the last of the organs to develop, but both are nearly ready now.  The lungs are developing surfactant now, which helps the alveoli expand.  Baby can turn their head, react to sounds and lights and blink their eyes. Vernix, the waxy substance that protects your baby’s skin while in the womb, is mostly gone now.  There is a small amount left to help the trip through the birth canal go smoothly. Your appetite may decrease now, as you have less room for everything, including your stomach, as the baby has grown larger.  Remember to

rest often because many sleepless nights are ahead!

Week 39A healthy range of weight is between 5 pounds and 11 ounces and 8 pounds 5 ounces.  Your baby is probably somewhere in this range now.  The umbilical cord doesn’t have any nerve endings (this means that you and your baby will not feel any pain when it is cut!) and is about 20 inches long and about ½ inch thick.  It’s pretty common for the umbilical cord to get knotted at this point, because things are so crowded inside the uterus. All of your baby’s organs, including the lungs are ready for birth now.  Your baby’s immune system is gaining strength at this point.  Right now, you are probably very uncomfortable and can hardly stand the wait.  Try to take it easy and rest when you can, long naps and reading can help you through the last few days of your pregnancy.  Remember that very few babies are born on their due date.

Week 40You’ve made it!!  Any day now your little one will arrive.  Don’t be surprised at how your baby looks after birth.  Their little heads can be misshapen and their skin may be discolored and have patchy looking rashes.  An average baby weighs about 7 ½ pounds and is about 21 ½ inches long at birth.  Every baby is different, though,

and soon you’ll get to meet your little one. Babies have more than seventy different reflexes when they are born.  These automatic, unlearned behaviors are necessary for survival.  While in the womb you provide your baby with antibodies and make their immune system stronger.  These immunities that you pass on to your baby

will stay with them for the first six months of their lives.  Because of your hormones passing on to the baby, your baby may have enlarged genitals when they are born.  Hormones can also cause both little boys and little girls to secrete milk from their nipples. Light exercise, such as walking, can help bring on labor now.  Try to relax and enjoy the last few days before your little one arrives.  Getting plenty of rest now will help you make it through the labor and delivery you have ahead.

The Baby is finally here!