Being pregnant is a great time to learn about your body and your baby. And no, you do not have to learn it all at once. It’s too much information to take in at one time and you won’t remember most of it as the pregnancy weeks go by. But you can get a quick overview of what is happening to your body as the baby develops inside you.
There are approximately 42 pregnancy weeks. Each week, something amazingly complex is occurring inside you, whether you are aware of it or not. You may experience symptoms of changes for months, and the miraculous journey results in a bonnie baby at the end of it.
But what’s really going on in there? Wouldn’t it be wonderful if you could understand how life is developing inside you? This is an opportunity to get in touch with your body and your baby so you can truly appreciate the miracle of life.
Pregnancy Week by Week
The following is an approximate description of your baby’s development through the pregnancy weeks. Since every woman is different, the changes mentioned below will differ from woman to woman.
Pregnancy Week 1
The first week of pregnancy is before conception occurs. The first week is your period cycle. The reason for this is that the due date is calculated from your last period before you got pregnant. So the last period needs to be counted as your first week of pregnancy.
Pregnancy Week 2
This is when your ovaries will produce an egg and your uterine wall will begin to develop. Your body will release FSH or follicle-stimulating hormones – this is what helps the egg to develop and mature. If you have a 28-day cycle, your ovaries will release an egg onto the fallopian tube by the end of week 2. This is called ovulation and any sexual activity around this time is bound to be highly productive. You are most likely to get pregnant at the time of ovulation.
Pregnancy Week 3
Week three of your incredible pregnancy will see the fertilised egg going through a process of cell division. What this means is that the fertilised egg will divide into two, then four, then six, and so on as it moves up the fallopian tubes and into the uterus. By the time it reaches the uterus, it looks like a tiny ball. This is called a morula, which will become hollow and then get filled with fluid. At this point, it is known as a blastocyst. At the end of the third pregnancy week, the blastocyst will attach itself to the wall of your uterus or the endometrium. This process is called implantation.
It is only when implantation has fully completed that pregnancy is said to have occurred. There are several reasons for this. Because it is only now that the pregnancy hormone hCG will be released and you will be able to tell that you are pregnant. Also, implantation is considered to be important as the uterine wall will provide the embryo with nutrition. And the site at which the implantation occurs will develop into the placenta.
Pregnancy Week 4
Your baby is now an embryo. The embryo has two layers of cells at this point – one layer is the hypoblast and the other is the epiblast – which will grow into the baby’s organs. The amnion and the yolk sac also develop around this time. The amnion will eventually fill with amniotic fluid and act as a shield for your baby to safely nestle in, while the yolk sac will nourish the embryo until the placenta is fully developed so it can take over.
Pregnancy Week 5
Up to this week in your pregnancy, the embryo has been a shapeless mass of cells. But now is when your baby will start to take shape. The embryo will develop a neural tube from the top to the bottom. This tube will eventually become your baby’s spinal chord and brain. There will be a bulge in the middle of the embryo where your baby’s heart will form. And the placenta will finally develop at this stage too. The placenta is your body’s way of nourishing the baby. So from now on, some of the nutrition from the food you eat will be transferred to your baby via the placenta.
Pregnancy Week 6
Do an ultrasound in this pregnancy week and you will most likely pick up the baby’s heartbeat. Little buds that will grow into the respiratory and digestive systems and the hands and the legs will also show up. The spinal chord and brain are growing at a very rapid pace right about now. The passageways that will grow into ears and the optic vesicles that will grow into eyes begin to form too.
Pregnancy Week 7
The umbilical cord makes its entry in pregnancy week 7. The lungs and digestive system continue to develop, as do the features of your baby’s face. A little hand will start to take shape too. It is around this week that your body will grow a mucous plug in the opening of your cervix so as to seal of the uterus for protection.
Pregnancy Week 8
Tiny fingers and tinier toes will begin to form this week. The joints of the arms have also developed a little to the point where the embryo can flex at the elbow and wrist. The eyes develop their colour around this time. The baby’s genitals begin to bud. And the intestines have developed till they are too large for your baby’s tiny tummy. So they will nestle in your umbilical chord for a few weeks.
Pregnancy Week 9
Your baby’s head is bigger than the body at this point. Which is what causes it to curve into the chest in a foetal position. Also, the tail of the spinal cord has practically disappeared. The nose is visible in profile, and the eyelids are beginning to form. The digestive tract continues its development, the intestines get longer, and the anus begins to form. The reproductive system of your baby will begin to take shape this week. So the testes or ovaries will begin to take shape. This pregnancy week is when your baby starts to move around a bit because the muscles begin to develop too. But you will not feel this movement as the embryo is still far too small.
Pregnancy Week 10
This is a pretty exciting week for your baby as all its main organs are complete and they start to work together. The tail of the spinal cord disappears altogether now, the fingers and toes start to separate into individual digits, and tooth buds begin to form. The embryo has now begun to look distinctly human.
Pregnancy Week 11
In the pregnancy weeks that have gone by, your baby has grown at a very rapid pace. But development will be much faster from now on. Your baby is now officially a foetus. It’s big head is even bigger now, accounting for half of its body size. The ears will form in more detail now, as will the reproductive system. However, the genitals will appear ambiguous till about your 14th pregnancy week.
Pregnancy Week 12
As you near the end of your first trimester, your baby’s digits will develop nails. The vocal chords will form, and the kidneys start to function. The baby’s intestines which were tucked into the umbilical chord will move into the foetus’ stomach as there is now enough space there.
Pregnancy Week 13
The second trimester of your pregnancy will see the completion of your placenta, which will provide your baby with nutrition and oxygen, and be responsible for removal of the baby’s waste. The placenta will release very high levels of the hormones progesterone and estrogen to help the pregnancy move along smoothly. Also, your baby’s eyelids have formed completely at this point.
Pregnancy Week 14
Your baby’s thyroid glands and genitals have completely developed now. Although the genitals may not be very clear on an ultrasound quite yet. Fine hairs called lanugo develop on the baby’s face. It will cover the whole body with time but will be shed just before you give birth.
Pregnancy Week 15
The hair will continue to grow on your baby’s head and eyebrows. Skeletal and muscle development also continue, so you may start to feel the baby moving about now.
Pregnancy Week 16
Your baby’s facial features have developed almost fully, allowing the foetus to frown or squint or make funny faces if it wants to.
Pregnancy Week 17
The placenta continues to grow as well to accommodate your growing baby. Right now it carries food and oxygen to your baby through thousands of blood vessels. Your baby is still quite a tiny little thing – only about 5 inches. As your pregnancy progresses, you will notice that your breasts grow in size as they prepare to feed the baby. Your breasts will feel quite full and heavy. The skin on your breasts stretches itself out because of the rapid pace of growth and your may be able to see your veins. You should get supportive bras to experience better comfort.
Pregnancy Week 18
Your baby’s ears have been developing all along. And they will move into their final position around this time. In a week or two from now, your baby will be able to hear. The eyes will also further develop. The biggest change in this pregnancy week is that the bones of the foetus will start to ossify or harden, starting with the legs and the clavicle.
Pregnancy Week 19
The most exciting development around this pregnancy week is that you will begin to feel the baby’s movements quite strongly. This is known as quickening. It may feel like a flutter or your tummy may growl as it would when you are hungry. Your baby needs a little more protection from now on. Which is why the foetus will develop brown fat to keep the baby warm not only in the womb but after birth as well. Another form of protection is the development of vernix caseosa, a waxy substance with the consistency of melted cheese that will cover your baby from head to toe to protect its delicate skin.
Pregnancy Week 20
Congratulations! You are halfway through your pregnancy. Under the protection of the vernix caseosa, the foetus’ skin will thicken and several layers will begin to form. As the baby is growing is size, you may feel the pressure on your bladder, kidneys, lungs, and stomach.
Pregnancy Week 21
Up to this point, the blood vessels of the foetus were produced by its liver and spleen. But from now on, the bone marrow spaces have developed so they will help in blood cell production. From the third trimester onward, the bone marrow will almost fully take over blood cell production. The intestines of your baby are developed enough at this point to be able to process sugars from the amniotic fluid.
Pregnancy Week 22
Your baby’s senses have been developing all along and are almost at completion in pregnancy week 22. The baby can now taste and feel. The reproductive system has also been undergoing continual development. At this stage, the testes will descend in boys, and the ovaries and vagina are fully formed in girls.
Pregnancy Week 23
You’ll feel tremendous joy as the baby will be doing a lot of kicking and moving about. However, your size will cause some general discomfort and you may have trouble sleeping. You may also feel overly anxious or get odd cramps and pains.
Pregnancy Week 24
The baby’s inner ear is fully developed now. Since balance depends on the inner ear, your baby can now understand that it is on its right or left side or if it is upside down. This is also the time when the baby’s lungs are beginning to produce surfactant, which is what prevents the lungs from collapsing in on themselves when we exhale.
Pregnancy Week 25
Great news about the baby – it can now hear you. So you can talk to it or sing and it will take it in. There will be a lot of foetal movement as the baby has developed almost a full range of motion and is curious about what each of its little body parts is capable of. Bad news for you though – you’ll experience frequent indigestion and heartburn because of the additional weight of the uterus on your organs.
Pregnancy Week 26
Weighing in at about 1 kg in this pregnancy week, your baby is still rather small, wrinkly, and relatively hairless. But that is being remedied as the hair on the head continues to grow, and eyelashes begin to show too.
Pregnancy Week 27
At this point, your baby pretty much looks like a small version of what it will look like when it is finally born. But it’s not quite ready yet as the immune system, liver and lungs have yet to fully develop. The foetus’ hearing grows sharper as well and it may be able to distinguish voices.
Pregnancy Week 28
Hair continues to grow on your baby, as do additional layers of fat. The brain also continues to develop.
Pregnancy Week 29
As your baby continues to grow, it will do everything to make its presence known. It can deliver some pretty hard punches and kicks that will have you gasping for breath, but not necessarily so. Try to keep tabs on its level of activity, and if you feel that it isn’t moving as much as it did, talk to your doctor.
Pregnancy Week 30
Your baby is about 10 inches long now. It continues to gain weight as more layers of fat are added to its tiny body. Your baby is also preparing for respiration. It cannot breathe in the amniotic fluid, of course. But it will mimic the motions of breathing through repetitive movements of the diaphragm.
Pregnancy Week 31
Since the kidneys and urinary tract developed long before now, your baby is urinating several times a day. Swallowing of the amniotic fluid is also continuously occurring. There is a standard level of fluid in the amniotic sac. If the level increases or decreases, there may be a problem. If there is excess fluid in your amniotic sac, it could mean that the baby is not swallowing as it should. And if there is not enough fluid, it indicates that your baby may have a problem with its kidneys and is unable to urinate properly. The only way to check this is through an ultrasound.
It is also around this time that your breasts will begin to produce colostrum. Colostrum has a different consistency for different women. It is not exactly milk, but it will provide your baby with nutrition for the first few days after it is born until the mammary glands start producing milk.
Pregnancy Week 32
The lanugo is starting to shed. But the hair on the head, eyelashes and eyebrows is apparent. Your baby is actually fully developed at this point and would survive if it chose to be born during this pregnancy week.
Pregnancy Week 33
The final few weeks of birth mostly see your baby putting on more weight. The extra layers of fat will help to keep it warm after birth. Your baby spends most of its time sleeping at this point. Research has shown that babies even dream at this point. The lungs are almost fully developed too.
Pregnancy Week 34
The lanugo has almost completely disappeared. And the coating of vernix is getting thicker. At this point, your baby should be in a position for delivery. Ideally, the baby should be headfirst so that it can easily slide out of the cervix. But there are times when the baby is bottom-first (breech baby), in which case a C-section will have to be performed.
Pregnancy Week 35
More fat continues to develop on your baby in preparation for its exit from the womb. Your baby weighs a little over 2 kg now and is already too large for your uterus. Since its really cramped in there, the baby cannot move around as much as before, but you will still get some forceful kicks now and then.
Pregnancy Week 36
More weight gain occurs. Your baby is a chubby 3 kg. If your baby is positioned headfirst, it is resting on your pelvic bone and the skull may starts to take on a pointy shape in anticipation of the baby’s exit through the narrow birth canal. This is called molding and is nature’s way of easing the already agonising process of childbirth. It is around this time that the baby descends into the pelvis in preparation for birth. This is called lightening or engagement. You may experience the sensations if you are in tune with your body.
Pregnancy Week 37
Remember that mucous plug we talked about earlier? That will fall off any time after this pregnancy week. Meanwhile, your baby has developed some nifty motor skills and can grasp with its fingers. If you shine a light against your abdomen, your baby is likely to turn towards it.
Pregnancy Week 38
While your baby is still getting a little fatter by the day, your weight gain may slow down or cease completely. If your baby is female, her labia will be fully developed by now. And as for a boy, the testicles will have descended into the scrotum. Your baby is low enough in your pelvis to press almost entirely into your bladder. You’ll barely be able to hold in your urine. You’ll make several trips to the bathroom all the time.
Pregnancy Week 39
This close to the end of term, your baby could literally be born any day now. The lanugo and vernix has vanished, and the antibodies that your body has been supplying to the baby through the placenta will keep the baby safe from infection for up to a year after it is born.
You may experience Braxton Hicks contractions as your uterus prepares for labour. These contractions may be just as terrifying and painful as real contractions, but they are simply uterine contractions performed by your body to prepare for the coming labour. Talk to your doctor about any pains or contractions.
Pregnancy Week 40
If your baby is born at this time, it will weigh approximately 4 kg and be about 20 inches long. Make sure that you prepare for labour well before this week by taking Lamaze classes and talking to your doctor about the different method and options for pain relief.
If you want your baby to be born on a certain day, you can opt for a C-section around this time. You’ll have a fully developed healthy baby who will not need any external life support systems or special care to keep it alive.
Pregnancy Week 41
From week 40 on, it’s really just waiting. You can speak to your doctor about inducing labour if you don’t want to wait any longer. But you can safely wait for another couple of weeks.
Pregnancy Week 42
It is rare for a baby to be born after 42 weeks. So your baby should arrive any day now if it hasn’t made its appearance already. All you have to do now is relax and prepare to welcome your child into the world.