Fetal Development


Heres all you need to know about what happens to your baby week by week throughout pregnancy.

Last Updated: Oct 22, 2020 11:29 GMT

Fetal Development
Fetal Development
Week  1

Your last ovum, after a futile wait for a sperm to fuse with, disappointedly departs your uterus along with the shedding of a little of your uterine lining. This is the first day of your menstruation. Ironically, this is when your potential to get pregnant in the next cycle begins.

Your partner’s sperms are already in the making now. His reproductive system produces millions of sperm cells every day. His sperm develops in his testicles and at the end of the development, they move through his epididymis for about 4 to 6 weeks, before they reach the sperm duct.

During your week 1 of pregnancy, that one sperm of his which shall mate your ovum in the coming week is most likely to be crawling through his epididymis. The sperms resemble a tadpole now with a head part and a short tail part. Their tails give them motility which is an important prerequisite for conception.

Week 2

A mature ovum from the ovary is released during week 2 into your fallopian tube. If you’ve wondered what the term ‘ovulation’ meant, this is it - ovulation is the release of ovum into your reproductive tract! When the ovum reaches the fallopian tube, chances are there that your man’s sperms are already waiting in there (if you had sex within five days before ovulation). If there is no sperm yet, your ovum will wait for 12-24 hours for a sperm to fertilize.

Unlike you who released only one egg cell in a cycle, your man has been producing millions of sperm cells every day. His sperms continue their journeys through epididymis until they reach the sperm duct. When he is sexually aroused, sperms stored in the sperm duct mixes with the fluids secreted by his seminal vesicles and prostrate glands on their way as they travel to their final exit during ejaculation into your vagina at the time of having sex.

Week 3

After long hours of travel and crossing-over of hurdles, the Mr. Right sperm managed to penetrate through your ovum. Once inside, the sperm’s genetic material fuses with that of your ovum. Hurray! Here’s a unique single cell carrying a unique set of genes and ready to kick start your pregnancy.

Your baby begins his or her journey as this single cell called a zygote. The all-excited little cell begins to divide itself to multiply exponentially. In 3-4 days, it grows from one cell to two; from two cells to four; four to eight and then to sixteen cells which makes a spherical ball called a morula. In the next 6 days, your tiny baby ball bounces and rolls through the fallopian tube on its way to the uterus. In the due course of its ride, it grows to a hundred cells clustered together to make a blastocyst.

Week 4

Your baby ball has rolled a long way and has now reached your uterus. Once in the uterus, she becomes what is called a blastocyst (still a primitive form of your baby) made of a group of around a hundred cells.

Week 4 is one of the eventful weeks for your baby blastocyst as she implants into your uterine lining, laying the foundation for her cozy womb to live and grow in the next nine months. Implantation connects your baby with the blood vessels on your uterine wall. And aha! You are beginning to mother your little thing with oxygen and nutrients through your blood.

Your baby blastocyst is branching out this week into an embryo and placenta. Embryo is what will grow into your baby in the coming weeks while the placenta will make the nourishment support system to your growing baby until she is born.

Also, an active growth sprout of your baby’s organ development is beginning now. The neural tube which will evolve to your baby’s brain and spinal cord is already established. Amniotic sac, the protective covering, and amniotic fluid, the cushion system for your growing baby, are also formed by now.

Week 5

Bring an orange seed to your imagination. Your baby is now the size of one! Yes, you might assume she is too small yet. But, the fact is her tiny form is into an enormous load of work now. Growing an entire human body with interconnected systems is indeed a lot of hard work!

At week 5, your baby is still an embryo. She is strongly implanted in your uterus by this time though it will take a few weeks before the placenta completes its development. If you take a peep inside your baby embryo now, you can find three distinct layers:

·         the ectoderm on the top,

·         the mesoderm at the middle, and

·         the endoderm making the innermost layer.

Sure, you are in no mood to decipher these terminologies! For a quicker understanding, visualize your 5-weeks-old baby as a hollow sphere; of the size of a pepper corn and having these three layers. The outer layer, ectoderm, makes the bedrock for her brain and spinal cord. It is from here that a neural tube is developing which will bloom into her nervous system and other body parts like nails, hair and skin in the coming months.

Much to your surprise, your baby’s heart is already forming its chambers this week. Even though they don’t look like chambers yet, her heart is almost ready to kick start to beat. It is the middle layer, mesoderm, from where this spectacular development sprouted out. Her muscular and skeletal systems too take their foundations from here.

Other internal organs - intestines, pancreas, lungs, liver - to name a few, are beginning to take shape from the inner layer, endoderm. So you see how busy she is into developing her entire major and minor body systems?!

Week 6

At week 6, your baby continues in its embryo form and is about the size of a sweet pea, shaped like a curled tadpole.

Have you started dreaming how your tiny bundle’s eyes and nose will look like? If not, now is a good time because this week his facial features are coming out. He is also busy forming cheeks, jaw and ears. And the secret of whose nose in the family he is going to take inspiration from is put into manifestation now.

His vital organs such as liver, lungs and kidneys are growing relentlessly. His hemispheres in his brain are developing and in fact, an EEG can pick up his brain waves now. His hands and feet are beginning to sprout from what looks like webbed buds. He has a thin layer of skin now, tender and almost transparent.

His heart, still in its primitive structure, has started to beat. At week 6, his heart beat may not be loud enough to be picked up by an ultrasound. However, do not underestimate his heart’s ability, for it is beating 100 to 150 times in a minute, which to your strange surprise, is twice that of an adult’s heart rate.

Week 7

Your baby’s hard work of last week has doubled her and now, at week 7 pregnancy, she is of the size of a blueberry.  Rapidly developing now is her brain. Around a hundred cells are newly formed every minute within her brain. This accounts why the head appears unusually large at the fetal stage.

One of the major developments this week is the umbilical cord. Umbilical cord joins your tiny bundle to your placenta and is already supplying oxygen and nutrients to her. Her body has also started producing wastes which are, as well, carried through the umbilical cord to your bloodstream.

Next to her heart, her kidneys and liver are getting ready to begin functioning. Around week 7 pregnancy, her kidneys may start to produce urine and her liver is busy producing red blood cells. Her arms and legs which were tiny buds last week are now extending out from the bud, appearing like paddles this week.

Week 8

At week 8 pregnancy, your baby’s little body parts are taking advanced shapes. The tiny features on her face which were etching out in the last two weeks are getting more defined contours now. The dark spot making the primitive eyes are protruding further this week. Her eyelids and upper lips are forming for the first time and the tip of her nose is almost visible now.

Her tail which made her look like a tadpole is retracting, leaving behind the tailbone. Her webbed fingers and toes are beginning to form ridges in-between them and will soon take their individual shapes and sizes.

Unbelievably, she is already moving inside your belly, though you might not feel her movements yet. The cells in her brain, in addition to growing exponentially, are forming neuronal connections between them setting up the early neural pathways. 

Week 9

Congratulate your baby! At 9 weeks pregnancy, he appears closer to a fetus than an embryo. As an embryo, his major organs were formed up until now while with the beginning of the fetus stage, the organs continue to develop to their mature forms. 

Your baby is now the size of a cherry. If you were to peep into your gestational sac, you’ll find it strange to see his head making almost half of his total length.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   

The tail which made him look like a tiny reptile disappears completely this week and his fetal version appears closer to a human now. His heart finishes its final touch with four distinct chambers. The sex organs which are going to make him either a boy or a girl are forming at this stage. However, none can read the secret now because the differentiation into either of the two hasn’t begun yet.

Your little body builder is also developing muscles at this time though not strong enough to make you feel them. You were awaiting the time when he will begin to kick and move around, weren’t you? To your big surprise, he is already doing it, but hold on tight for a few more weeks before you can get a clue of it.

Week 10

As you complete one fourth of your pregnancy this week, imagine a little strawberry sitting inside your belly. At week 10 pregnancy, your baby in her fetal form is hustling in rapid growth and development of her body.

She is making her teeth this week. No, don’t get startled! She’s not going to be born with teeth. Neither is she going to get them until she is a few months after birth. Her teeth are just budding in their Lilliputian forms under the gums, this week. And at least for the next fourteen months, they will remain hidden with their roots getting nourished and strengthened. That is why it is important that your body has sufficient vitamin D levels.

Also, this week, tiny, bony protrusions in her arms and legs at the areas of knees, ankles, elbows and wrists are shaping out. In fact, she can flex her arms at the wrists; she can bend and stretch her arms at the elbows; her legs can move around the hip joints and her little palms can reach her heart now.

Her little body is carving out more intricate elements. Her eyebrows are beginning to grow. Her nails are forming and tiny hairs are shooting on her baby skin.

Week 11

At week 11 of your pregnancy, your baby is as big as a fig. If your baby is a girl, her ovaries are developing this week. If a boy, man, he is already producing testosterone! Though his or her genitals get recognizable by the end of this week, it may take a few more weeks before your OB can read your baby’s gender.

His facial features are undergoing constant metamorphosis to look more like a human. His ears are moving closer to where they ought to be positioned. Nasal passages on his nose are beginning to open up. You’ll be surprised to know that a tiny tongue is forming inside her mouth and in fact, he now has a palate which can soon begin to recognize tastes.

Can you believe that your little baby is actually breathing small amounts of amniotic fluid every day? In fact his developing lungs are filled with amniotic fluid and he is practicing breathing the fluid before he can breathe in air after birth.

His bones in the arms and legs are hardening, and he can now happily stretch and roll his body inside the womb. The webs on his palms and feet gradually disappear. Instead, distinct digits that will make his fingers and toes can be visible soon.

Week 12

Your little busy bee is as big as a lime at week 12 pregnancy. If you try teasing your baby by gently prodding your belly, she might actually be reacting to it. Although you may not see or feel her response, an ultrasound can capture her annoyance of being disturbed during her nap. This response is because of her newly developed reflexes. She can flex her fingers and curl up her toes now, in addition to bend and stretch her knees.

Her eyelids are fused together at this stage. They will remain so until week 27. Her digestive system is beginning to function by causing peristaltic movements in the stomach. The contraction and relaxation of muscles in the stomach are going to help your baby in digestion when she arrives out.

Her bones have developed within, distinct soft tissues, bone marrow. The bone marrow now begins to make white blood cells, the fighter cells of her body.

Week 13

At week 13 of your pregnancy, the little munchkin inside you has reached the size of a peach and she is continuing to grow in leaps and bounds. All along, her head appeared huge for her tiny body. But from this week on, her arms are getting longer and her entire body is picking up zeal to match the head’s size.

If you could see your baby in an ultrasound now, you may be surprised to see her sucking her thumb. Yeah, babies learn to suck their fingers even while they are in the womb. That is why it is unnatural to force a newborn to pull her thumbs away from her mouth. Aha! This is just the beginning; there is much more you will have to think about parenting, in the coming days.

Also this week, her vocal chords are developing. All that gagas and gugus that her infant version would sound like one day is set to begin their journey now, though it is still a long way before you can hear them. Can you even imagine tiny fingerprints on her tiny palms? Behold, they are beginning to form this week!

Almost all her organ systems are formed by now. Her intestines are getting their form completed and are moving to their destined position in her body. And all of the eggs that her ovaries would accommodate in her lifetime, which is over two million in number, are already developed.

Week 14

Your tiny tot, now at week 14 pregnancy, is of the size of a lemon. All his organs have completed their formation and some are continuing to mature or grow. You have been reading how your baby was developing all these weeks. Don’t be surprised, there is more to happen in the coming months too.

He is uncurling more and more in his fetal position; yawning, waving and sucking his thumbs inside the womb most of the time. A few moms-to-be can begin to feel the kicks by now. If you aren’t, keep calm, the football player is warming up your belly and you will soon watch the match.

His face is undergoing constant changes. This week, his facial muscles are in action, making a lot of faces. Also, the roof of his mouth is nearing completion.

His liver is now taking the additional role of producing bile apart from making red blood cells. His spleen is busy too in assisting making red blood cells. That’s some amazing development, isn’t it? His bone marrow is still maturing which will soon take up the red blood cell formation.

His intestines are also getting functional. They make meconium, your baby’s first poop. If you are growing a prince, his prostate gland is forming now. If it’s a cute little princess inside, her ovaries are descending down to take its final position.

Week 15

Your baby at week 15 pregnancy is as big as a navel orange. Believe it or not, he is quite a big boy now and knows how to keep himself busy the whole day. Okay, when he is out, it could be a different story altogether, mommy!

Some babies are born like teddies. No, we don’t mean a human face with a snout or clumsy limbs! Like teddy bears, babies can have a lot of hair all over their new-born bodies. This is because, your baby is developing short, hairy sprouts called lanugo. In most babies, lanugo is shed off at around 35 weeks. Some babies, however, born at 38 or 39 weeks can still have lanugo on them.

The primary role of lanugo is to hold vernix caseosa on the skin. Vernix is the whitish, fatty covering on the baby’s skin. It helps to regulate baby’s body temperature, protects baby’s skin and helps labour by providing lubrication. And it’s all developing on your baby’s delicate skin this week.

In the last few weeks, baby’s arms were extending. Now it’s the turn of his legs. They are outgrowing the length of the arms, making his limbs more proportionate with respect to his head and torso.

Week 16

At week 16 pregnancy, your baby is close to an avocado in size. Your baby’s eyes are undergoing a critical development this week. They are becoming sensitive to outside light. Even though her eyes are closed now, she can still perceive rays of light behind the shut eyelids. In fact, she can show responses to light stimuli by moving herself away from the source of light. Studies show that going out in sunlight at this time can help healthy development of baby’s eyes. If it wouldn’t hurt to take a walk during the day, you should.

Parallel to your little one’s progress with vision, her hearing ability too is preparing for major developments this week. Most babies at week 16 pregnancy can in fact hear your voice. When she is out into this world, the first voice she is going to recognize is your’s. Keep singing aloud a song you have self-composed exclusively for your unborn bundle. And when she is in your arms, she’ll awesome you by acknowledging the familiarity of her favorite tune in mama’s voice. It’s okay even if it’s not your own song. Simply humming a loving melody can as well intensify your bond with her.

You still don’t believe your baby is moving inside, do you? Perhaps, this week, you will begin to! 16 weeks is a fair time for many moms-to-be to feel mild kicks (called quickening). The more your baby gets bigger and the more your bump is coming out, the more you are going to experience the full-some baby-in-action in the coming weeks. Now could just be a teasing trailer time.

Week 17

At week 17 of pregnancy, your baby is as big as a pomegranate. Wonder what he is up to this week? You'll be amused to know that he is busy honing his skills of sucking and swallowing now. If you couldn't make the connection yet, listen to this mommy - he is already preparing for his feeds outside his womb life! Be it your bosom or a bottle in the future, he is learning sucking and swallowing at which he'll become a pro even before he is born.

Your baby is actively developing fat beneath his skin. It keeps him cozy in addition to acting as an energy source. And yes, it makes him appear cute after birth. His sweat glands are also developing.

His bones which were more like soft cartilages are hardening to become true bony structures. His limbs are nearly proportionate to his head size now.

Week 18

Your baby at week 18 pregnancy is of the size of a sweet potato, making wiggles and jiggles inside all day. Don’t be surprised if you don’t feel all that all day. There is enough insulation between your baby and your outer belly which cuts down the chances for you to feel your baby move.

She is up to more insulation generators this week. A fatty substance called myelin is beginning to form around her nerve cells. Myelin provides insulation to the nerve cells it surrounds. With her nervous system actively developing, myelin sheaths can speed up the process of transmission of electrical impulses between neurons. In simple terms, her nervous system is doing big progress in its development.

As you might know already, your little listener is becoming sharper on her hearing skills. She is getting used to a variety of sounds around. Can you name a few of these sounds? Why, it should be your voice and at times her dad’s voice. Quite obvious, is it not? Bah! C’mon mama, you don’t have to think out-of-the-box, just see-inside-your-body! She can now perceive the sound of your heart beat, your stomach ramblings, the gurgling of water through your food pipe and even your hiccups. Does it make you guess how close she is to your body?

Week 19

Your baby at week 19 pregnancy is as huge as a mango. So, what’s going on within your mango-sized munchkin? The important development this week is the formation of vernix caseosa. Vernix is a cheese-like substance that begins to cover your baby’s skin. It is primarily made of cells that are shed by the fetal skin, called sebum.

Vernix protects your baby’s skin from the amniotic fluid. Well, why should something do that job in the first place? Let’s discuss how your skin would become if you were to soak in a pool of water for nine months? Wrinkled like an old prune, isn’t it? And we don’t want that to happen to our babies! In other words, vernix acts like an anti-wrinkle cream for your baby protecting her soft skin from shriveling.

His or her genitals are still developing though most likely, can be identified in an ultrasound by now. The hairs on her head are beginning to bud, making her face look closer to a human.

Week 20

At week 20 pregnancy, your baby is as big as a banana. He is listening, he is yawning, he is napping, he is sucking his thumbs, he is swallowing fluids and he is in fact producing his first poop, meconium – in short, he is just too busy growing!

Baby’s sex organs are becoming well-defined to be captured and identified on an ultrasound sooner this week, if not already by now. Your baby’s genitals began to form at about 7 weeks pregnancy though the differentiation into male or female genitalia did not happen yet.

By 16 weeks, if your baby was to grow to a boy, the amount of the male reproductive hormone, testosterone, produced by your baby would have been as high as in an adult. It is testosterone which directs the formation and the lengthening of penis. By now, at 20 weeks, testosterone levels drop down to what a boy in early puberty would have. His testicles still remain in his abdomen and shall not descend into his scrotum until 26 weeks.

In the case of a baby girl, the external genitals do not undergo major changes since their formation. However, ovaries produce millions of early stage eggs and by week 20, if you are carrying a girl, she’ll have 7 million eggs in her ovaries. Yes, you read it right!

Week 21

Your baby at week 21 pregnancy is as long as a carrot. Did you notice in your last week's ultrasound, that the sonographer measured her length from 'Crown to Rump', instead of 'Crown to Heels'? Oh yeah, she is a big girl now though she is only half of how big she'll be at birth!

Your baby's digestive system is making progress. The tastes buds on the palate are beginning to give her a glimpse of what different foods taste like. But wait, she isn't having food yet, and neither is she going to have solids until a few months after birth.

Remember, we have been saying to you that she is now swallowing a little of amniotic fluid every day? And that's from where she gets to taste what you eat. Some studies show that babies who are exposed to tastes of some foods in the womb, are more likely to gain preference for the same foods when they begin to have solids. C'mon mommy, isn't that a good reason to include more veggies in your diet?

Her intestines are producing small amounts of meconium upon digestion and after absorption of small amounts of amniotic fluid. It gets collected in her intestines. After the baby is born, it is released as baby’s first poo, meconium, usually black in color.

Week 22

Your baby at week 22 pregnancy is quite huge now, of the size of a coconut. By now you may have experimented quite a few times how your baby reacts to flashing light over your belly. Did he wiggle? Or did he kick? It’s alright if he didn’t respond. It isn’t a thing to worry; maybe it was his nap time.

His eyes are completely formed now though his eyelids will still remain closed until another six weeks. Nevertheless, his eye balls can make rapid movements underneath the closed lids. What is still missing about his eyes is his eye color which is determined by the iris. At week 22, his irises do not carry pigments yet.  It may take around nine months after the baby is out for a permanent eye color to form.                

Another major milestone your baby reaches this week is the developed sense of touch. The nerve connections that are responsible for him to feel touch stimuli are now formed. Amazed by this new awareness of his body, he may try to cuddle his cheeks and stroke his arms.

Your baby’s pancreas is also developing fast now. The alpha and beta cells of the pancreas which are involved in the production of the blood-sugar-regulating-hormones are developed. They are functional now, making high levels of glucagon and relatively lower levels of insulin.

Week 23

At week 23 pregnancy, your baby is of the size of a grapefruit. From now on, she’ll be busy multiplying her weight and filling herself with fat deposits. Yes, her chubby cheeks and chick thighs are a lot of hard work you see!

Though a tiny fetus, she may have developed a sleep-wake cycle by now. If you can track her movements 3 or 4 days subsequently, you may find a pattern. You will know that your baby is awake if you feel a lot of kicks and slithers under your belly. If there hasn’t been a movement for some time, she might be quietly napping.

Some studies report that babies in the womb can also begin to dream. Their sleep cycles can have the rapid eye movement (REM) phase of sleep alternating with the non-REM sleep, just like adults.

Week 24

At week 24 pregnancy, your baby is as big as a papaya. This week, your baby is reaching a critical fetal milestone – the viable pregnancy age. If babies were to be born prematurely after 24 weeks, it is possible for them to survive outside the womb, under neonatal intensive care. It does not mean that they can survive as easily as full-term babies. It would require intense medical intervention to support their lives outside the womb at this age. Yet, if the mother or the fetus face a complication which requires bringing the baby out, 24 weeks is the minimum cutoff time to attempt doing it, which is why 24 weeks is marked as the viable pregnancy age.

Rapid growth, maturation and expansion of your baby’s respiratory system begin now and shall continue until birth. A major development happening at 24 weeks is that your baby’s lungs are beginning to produce surfactant. If you didn’t know earlier, your baby has already started practicing breathing. She is breathing the fluid that fills your amniotic sac. However, soon after she is out of the womb, she will begin to breathe air, taking in oxygen and exhaling out carbon dioxide. An important substance that helps respiration is surfactant, produced by tiny cells in the lungs. The role of surfactant is to reduce the surface tension of fluids in the lungs, providing expanded space for gas exchange.

Week 25

At week 25 pregnancy, your baby is as big as a cauliflower. That sounds really big, doesn't it? Your baby this week is continuing growing a lot of hair and a lot more fat.

You have been reading a bunch about your baby's lung development in the recent weeks. Here's one more to it, this week - her lungs are forming blood vessels, bringing life into it.

Another step to bring breathing close to reality is the development of nose. Her nostrils are unplugged now and can you believe that she is in fact breathing through her nose? She is practicing breathing amniotic fluid now (we can hear you wondering aloud how humanly possible it is). This practice is truly important to her to begin breathing air when she's born. Recent studies show that nose of the fetus can also begin to smell this week. If you are now thinking about what she could smell, we guess it must be her urine. Yeah, she’s peeing into the amniotic fluid.

Week 26

Your baby is of the size of an egg plant now. She is continuing to practice taking breaths with amniotic fluid. Her senses are undergoing new development this week.

Her eyes are fully developed by now. By full development, we mean that the inside of her eyes has formed the major connections. Her eyelashes and eyebrows are formed. Her eyelids have been fused together and closed shut all these months. Though they are slowly beginning to separate and open this week, they will not open completely until 28 weeks.

Your baby can very well perceive light and shadow at this point. A flash of light beamed at your belly can make your baby sense the external light. Some babies tend to respond to bright light from outside by moving their face away from it. Some babies make jerky movements in response to sudden flashes of lights. What does your little girl or boy up to? Try it out, Mommy! You are sure to cherish these loving moments of your pregnancy even after years.

Your baby’s hearing sense is also maturing. Since sound can easily cross your uterus, she is listening to many of your conversations with people around. Remember to speak lovingly and politely for your tone can pass your feelings too to the growing bundle.

Week 27

At week 27 pregnancy, your baby is as big as a cauliflower. The major areas of his development now are his lungs, brain, eyes, ears and pretty much all of his senses. His eyelids will be soon open wide and he will be able to see what’s happening in your womb. His hearing is getting sharper. In fact, he can now say apart who is speaking – the mom or the dad. His taste buds too are exploring a little of his first oral feed, the amniotic fluid.

Quite often, you might feel jerks from inside your tummy as though your baby is having hiccups. Will you be surprised to know that your baby is really having hiccups? The exact reason why fetuses get hiccups in the womb is unknown. However, it is an experience too common for most pregnancies. For the first few times, you may feel you need to act upon to relieve him from the flicks. But, know that a baby’s hiccups are not known to sign a distress. Rather, it could be nature’s way to make the little one adapt to his speeding up growth. So, sit back and relax, Mommy. Simply watch your bump bounce in joy!

Week 28

Your baby, at 28 weeks pregnancy, is of the size of an egg plant. Her layers of fat continue to fill in, smoothing out her skin. If not for these fat deposits, she would appear wrinkled at birth. Here are some of the major developments happening to your growing fetus inside your expanding uterus this week:

If a baby was to be born at week 28, he or she can breathe on his or her own. The alveoli, important breathing components inside the fetal lungs are mature enough now. A premature baby at this stage can survive with intensiv medical aid though the lungs continue to develop until 8 years of age.

Bling! Your little sweet’s eyelids are open now. In fact, she can flutter her eyelashes. And, yes, she can take a peek into what’s happening in the womb. Imagine you have twins. They are going to meet each other this week (yeah, even before you do!) and perhaps, touch and fondle too!

If you have an ultrasound this week, you can observe your baby doing a lot of surprising gestures - sticking out the tongue, hiccups, and you may even catch her in the REM sleep state with moving eyeballs under closed lids. Did you know that babies are believed to begin dreaming in the womb, even before they are born?

Week 29

Your baby at 29 weeks is of the size of a butternut squash. His brain is enormously expanding, making new brain cells and nerve connections every day.

If you are carrying a boy, his testicles are having a fun ride down his pelvis. Soon it will reach its destination at the scrotum. His bones are continuing to grow harder and stronger. Yeah, all those strong punches you feel are a result of this development.

Vernix, the fatty coat on his skin may begin to fall away from this week onwards. For most babies, it completely withers away before the due date; however, some babies, especially those born a few days earlier than the due date can still hoard vernix at the time of birth.

Week 30

Your baby at 30 weeks now is as big as a huge cabbage. He is moving inside your belly in all directions he can and trying to explore his newly-developed sensation of touch. His brain has been expanding and continues to expand further.

Have you ever wondered how a little brain can accommodate an enormously increasing growth? If you remember seeing an image of a brain, it has extensive grooves and ridges, making numerous convolutions all over. The outer surface of your little one’s brain has started to make convolutions now, helping the process of adding many more nerve cells to the brain. And these are what going to bear all your baby’s essential life systems, thinking, creativity and imagination.

A few babies, by now might turn over with their heads downward into the pelvic inlet, towards the cervix, a process called as fetal engagement. However, most babies are known to get engaged two weeks before birth. Well, it’s so much up to your baby of what he wants to do.

One of the important developments this week is that your baby’s bone marrow is starting to take up the job of producing red blood cells. All along in the second trimester, his liver was the primary source of red blood cells but now bone marrow is fully into its functioning form of red blood cells production.

Week 31       

At 31 weeks pregnancy, your baby is of the size of a coconut. It is the time of rapid weight gain now. She might be closer to her birth height perhaps because of the lesser space available now to expand lengthwise. With all her systems in place, her senses developing rapidly and her brain cells multiplying enormously, your little bundle is making the final touches to her portrait.

Talking about senses, her eyes can now partially see light and darkness; her ears are listening keenly to you, her fingers and toes are trying to touch and hold whatever is possible to reach and in fact, her taste buds too are experiencing the taste of the amniotic fluid. However, she hasn’t begun to smell yet. This is because she is still in the waters and breathing amniotic fluid. She’ll begin to smell when she begins breathing air.

The kidneys are actively producing urine. If a girl, her clitoris is nearly developed and of course, for a boy, his testicles are too close to their destination. Another important development happening at 31 weeks is the differentiation of the islet of Langerhans in her pancreas. These cells will mature to make some of the most important hormones of the digestive system.

Week 32

At 32 weeks pregnancy, your baby is as big as a squash. His organs are almost developed and ready to begin life outside the womb. Yet, he will continue to develop and grow bigger in the next eight weeks. His skin which was transparent all along showing through it the underlying blood vessels is now slowly becoming opaque.  

An important progress between 32 to 38 weeks is the ‘dropping’ down of the baby’s head. Also called fetal engagement, babies around this time decide to drop lower within your pelvic inlet. The wide available space at the bottom can accommodate your baby’s head more easily now. A natural birth process always involves the head coming out first. And that’s exactly your baby is preparing himself to. However, some babies won’t feel like dropping down until labor and that’s normal too.

Week 33

Your baby at 33 weeks pregnancy is as big as a pineapple. If you could get a peep into her brain anatomy now, you will be amazed with the busy networking of nerve connections going in and out of her little brain. Her brain is continuing to produce new cells and by birth it will reach around 100 billion cells – that’s the number of stars on a clear night sky!

Your baby’s bones are hardening and taking their final shape except those on the top of her head. The bones on the topmost part of your baby’s head are soft and do not join yet. They make a kite-shaped gap of around 4 to 5 cm in between them. Called soft spot or fontanelle, it is designed this way to allow easy pass through of baby’s head in the birth canal during birth. The two bone plates on the top can slide over each other - called moulding – during birth. As your baby’s brain will continue to grow during the first year after birth, the soft spot facilitates the rapid expansion and doesn’t close until your baby is around 18 months of age.

She is also beginning now to develop her immune system. From now until birth, antibodies are passed from mother to the baby through the placenta.

Week 34

Your baby at 34 weeks pregnancy is of the size of a cantaloupe. She is nearing the safer zone, that is, if you were to get into preterm labor at week 34, she is going to do fine outside under a few days of neonatal care. Her lungs are mature enough by now to survive outside through breathing.

She has been religiously practicing sucking and swallowing. That’s nature’s way to help your baby latch on to your breasts for her feeds after birth. The fatty covering of your baby’s skin, Vernix, begins to thicken now, providing warmth to her. However, vernix will soon begin to get laid off. Most full-term babies are born without vernix.

Her hearing is well-developed by now. Don’t miss to feed her the excitement of hearing you sing a lullaby for her or hear you narrate a loving story of her conception. You might be aware that she has been peeing into the amniotic fluid. Do you also know that her first poo, called meconium, is already collected inside her intestines? Babies usually release meconium soon after birth. It is dark in color with tinges of green and black.

Week 35

Your baby is as big as a honeydew melon at 35 weeks pregnancy. He looks almost like how he would at birth. His systems are fully formed and he’s busy padding up fat and gaining weight. There isn’t much room in the womb now to turn around the way he likes and have fun. Nevertheless, he is trying as much as he can to move and kick.

Most babies by now have their heads down, in a process called engagement. Some pregnant moms can feel when the baby inside comes to the engaged position though not all can identify. The head down position is a sign that the baby is coming in alignment with natural birthing. It doesn’t mean that you are ready to go into labor but just that baby and your body are gearing up to the D-day slowly. Some babies can engage even at the last minute, after labor starts. A few babies might not turn head down at all. They’ll have their legs towards the cervix, a position called breech.

Week 36

Your baby at 36 weeks pregnancy is as big as a bunch of bananas. She has almost reached her baby form from a fetus. Vernix, the whitish waxy substance on her skin and the downy hair are already shed off into the amniotic fluid. To your surprise, your little one might actually swallow them from the amniotic fluid. That is what makes meconium, her first poo after birth, black in color.

Your baby is continuing to put up baby fat which would make almost 15% of her birth weight. From this week on, your baby gains roughly half a pound a week. Her lungs are developed enough to survive the outside life though they haven’t started breathing air yet. Her digestive system though developed isn’t fully functional yet as most of her nutrients have been coming from the mother through the placenta.

Week 37

Your baby at 37 weeks is as big as a honeydew melon. Though on an ultrasound he might look as good as a newborn, some of his systems are still continuing to grow and mature. His hand dexterity at grabbing using fingers is building up. Be ready to witness those cute little fingers clinging on to your top very soon.

Your baby is taking loads of practice at sucking his thumb. This is going to help him to latch on your breasts for his first feed soon. Swallowing is another activity he is gaining mastery over. Whoa! So when he is out, he is already an expert at these two functions!

The antibodies he would require to battle any germs he might acquire during birth are now passed from your blood through the placenta. His immune system is developing as well, though it can take a few years after his birth to build a strong immune system. Soon after birth, your breast milk will take the role of supplying antibodies.

Week 38

Your baby at 38 weeks pregnancy is of the length of a leek. She may be more on the quiet side now as there isn't much room in the womb for all of her menaces; although she is quite active. If there should be one marked difference in her appearance between now and at birth, it would be her chubby cheeks and those chick thighs. Yeah, she is adding up more and more fat which all of you are going to adore, kiss and cuddle in a few weeks. We know how you can’t wait for that!

For boys, the testicles must have descended down into the scrotum by now though it is still alright if it hasn't happened yet. In fact, it can happen even after birth. Her lungs are doing its job of becoming to its mature form in order to take up the big task of breathing air the minute she'll be out.

The waxy, hairy substances, vernix and lanugo, on her skin are almost shredded off into the amniotic fluid and the left-over are being worked on too. On the top, on the other hand, your baby might have hair grown to about a few centimeters in length on the head when she's born.

Week 39

Big cheers to your little munchkin! She's a full-term baby now at 39 weeks pregnancy. That is, even if you have to deliver your baby tonight - a week earlier than the due date - she will be as fine as a 40-weeks baby. She is of the size of a pumpkin now. So if you are wondering what's left to happen with your baby this week, there's actually little. Apart from her lungs continuing to mature and brain continuing to expand (which anyways will keep happening post birth as well) there isn't a significant milestone with your baby's development at 39 weeks pregnancy.

What's important about your baby this week is her position inside the womb. Most likely (and what we want), she must be in the head-down position with her face facing your spine. This is what is going to make vaginal delivery possible. If your baby has her bottoms or feet down (called 'breech' position), your OB might either suggest for a manual manipulation to change her position or on the safer side, suggest a C-section.

Week 40

At week 40 pregnancy, imagine your baby of the size of a pumpkin or a watermelon. She has grown to whatever and how much she can inside the womb. And is about to take the exit! But, having said that, her growth doesn’t stop when your pregnancy hits the week 40 mark. Her hair and nails continue to grow. Her lungs are developing as well.


If you show no signs of labor (or even if you do), your OB might want to check how the baby is doing inside. This is to assess whether it is advisable or not to wait for natural labor to begin. A Biophysical profile (BPP) which includes a nonstress test (NST) is the common test to check on the baby.


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