Week By Week Pregnancy Transformations

Pregnancy can be one of the most beautiful, and overwhelming things. While mom and dad are just waiting for this new baby to come into their lives, they may be wondering what is going on in the body. Since there is no way that mom and dad can just check in to see what has changed, they rely on information from the medical and professional world to inform them of the changes that are happening.

When we stop and think about it, we realize that while 9 months may seem long, it really is a short period of time to grow a whole human being. When we think of every organ, every nerve, and every milestone that has to be hit for a baby to come out at the end, it can seem amazing.


It is true that every single week there is something happening in the womb. Some weeks are more “action-packed” than others, but changes are always happening. From the moment an egg is fertilized, changes are happening, and happening fast.

RELATED: Second Trimester Fetal Brain Growth Changes Are What Make Humans Unique

We are going to go through every single week of pregnancy and explain what is happening to the baby, and what they are developing.

First Trimester

According to What To Expect, the first trimester is when a lot of the action happens, and before mom even has a baby bump, the basics of the baby are already formed but let’s take a closer look at what is happening as every week goes by .

Weeks 1 & 2

These weeks are grouped together because ether is not exactly a baby in there yet. This is when conception happens, and pregnancies are dated based on the last day of a woman’s menstrual cycle. This is when the body is getting ready to ovulate, and the uterus is getting ready to home a fertilized egg.

Week 3

This is the week when a fertilized egg travels down the fallopian tubes, and implants into the uterine wall. Congratulations! At this point, you are officially pregnant and carrying a developing baby. The blastocyst will now divide, and it will take the fertilized egg about 4 to 5 days to travel to the uterus.

Week 4

The fertilized egg has not made its way to the uterus and has been implanted in the uterine wall. It is not splitting into two groups, one will form the baby, and the other will form the placenta. Mom may not know that she is pregnant yet.

Week 5

At this point, the placenta is starting to form, and mom likely is feeling some symptoms and starting to think about taking a pregnancy test. The “mass of cells” is now called an embryo, and it is starting to look like a very tiny fetus. The neural tube (spinal cord and brain) is starting to form.

Week 6

The baby’s face is starting to form with cheeks, chin, and jaws. The heart is also starting to beat. At this point, your little baby looks just like a tadpole, and this includes a tiny “tail.”

Week 7

This is the week your baby gets its umbilical cord, and it will start working to deliver nutrients and oxygen. The mucus plug is also starting to form in the mother’s cervix to help protect. Your baby is also developing webbed hands and feet.

Week 8

The baby is starting to form its retinas, and its genitals are starting to develop. By the end of this momentous week, all of their essential organs and body systems are starting to develop.

Week 9

If you could see your baby now, you would see tiny muscles starting to form. The heart is beating loudly now and will be able to be heard on ultrasound, and the “tail” we were talking about earlier is now all gone.

Week 10

This week is fascinating because deep in their gums, your baby is already growing its teeth. The stomach is producing digestive juices and the kidneys are starting to make large amounts of urine. They are also getting their bones and cartilage.

Week 11

The baby’s ears are starting to move into the right position, and their fingers and toes are starting to separate and look like real little baby hands. They are also getting fingernails

Week 12

Your baby’s intestines were previously stored in the umbilical cord, but they are now moving into their body, and their body has started to make hormones.

Week 13

Your baby now has eyes, but their eyelids are fused shut to protect them. They are now forming their vocal cords and their body is starting to become more proportioned.

Second Trimester

The second trimester is when a lot of women start to feel better, and the morning sickness ends. However, there is still a lot of development happening, according to KidsHealth, and here is what is going on.

Week 14

Your baby is now developing hairs on its face and the rest of its body. This will help protect them in the womb. Their genitals are now fully developed.

Week 15

This is when your baby really starts to work on their skeletal system, and they are building their strength by moving a lot in the womb. Hair is continuing to grow, and their eyebrows are filling out.

Week 16

Your baby is now capable of holding its head up, and they have developed its facial muscles, which means it can make all kinds of expressions in the womb.

Week 17

Your baby is still very tiny, but its placenta has grown a lot. It has grown so that it can accommodate the growth that your baby is going to start going through.

Week 18

The ears have now moved to their normal resting place, and their little body is working on the ability to hear. Their eyes are also facing forwards now, and are getting ready to see the world. This is the week all the bones in your baby’s body will start to harden.

Week 19

The baby is now covered in vernix, the white and waxy substance that protects its skin from being in liquid all the time. This is when the baby will start developing “brown fat,” which will keep the baby warm after it is born.

Week 20

Your baby has grown substantially, and it may now start putting pressure on your body. The skin is getting thicker, and the hair and nails continue to grow.

Week 21

The intestines are now developed enough that sugar can be absorbed into the amniotic fluid, and your baby is now practicing swallowing, which means the body is building its first bowel movement.

Week 22

Your baby is working on its five senses now, and its taste buds have started to form. The brain and nerve endings are done developing, so your baby can experience touch. Your baby may start sucking their thumb this week.

Week 23

The skin on your baby continues to be looser, giving them a wrinkled look. Thanks to medical advancements, your baby may survive if born this week.

Week 24

The inner ear is now completely developed, and this controls balance, and this means your baby can likely feel when they are upside down.

Week 25

It is likely that your baby can hear you now, so make sure you (and your partner) continue to talk, sing and read books to the baby.

Week 26

Your baby’s eyes are getting ready to open and look around. Eyelashes, and hair on the top of the head, are also starting to really grow.

Third Trimester

This is it, the home stretch, and your pregnancy is almost over. This can be one of the hardest trimesters as the baby gets later, but according to The Bump, mom can expect these changes every week:

Week 27

The baby is now practicing breathing, and they are working on building their lung capacity and strength, so they can take their first real breath

Week 28

The baby is now going through massive growth, and they are also experiencing times when they are awake, and when they are asleep.

Week 29

The baby is getting pretty cramped in there, and they are growing at a rapid pace, putting pressure on the mom’s body. Much of the third-trimester development is gaining weight.

Week 30

Only ten weeks to go. Baby has a good amount of hair now, and they are opening their eyes and looking around. They are practicing grabbing onto things.

Week 31

All the baby’s five senses are now fully developed, and their eyes can now react to light. Their brain and nerve development has kicked into full gear.

Week 32

Baby is likely in a head-down position now, and they are getting ready to enter the world. Most of their development is over, and they are now just working on breathing.

Week 33

Baby is now coordinating their breathing with sucking, and swallowing, which will allow them to eat when they enter the world.

Week 34

The baby now looks almost exactly as it will be when it is born, they just need to put on a bit more weight. They now have their completed fingernails.

Week 35

Their hearing is now fully developed, and they are ready to listen to all the sounds of the world.

Week 36

This is the week when the baby’s liver and kidneys are done developing, and ready to work. The immune system is also ready to go.

Week 37

It may be normal that baby could come at any point from here. Baby is now just practicing their skills, waiting for the big moment.

Week 38

Baby is starting to get rid of the vernix covering their skin, and they are also working on that first poop.

Week 39

Baby can flex their limbs now, and their brain continues to develop (which is OK, because it will continue to develop for years after birth).

Week 40

Baby is ready to go now, and if mom hasn’t gone into labor, she may need to talk about future plans to encourage the little one to enter the world.

Sources: What To Expect, KidsHealth, The Bump

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