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Your baby's growth chart

In this growth guide, you will read what is happening week by week. At the bottom of the page, the first weeks (1 through 5) are explained in more detail.

Week 1

Week 1: your first week of pregnancy

You just had your last period, but officially this is already your first week of pregnancy. It is usually difficult to determine when conception occurs. What is certain is the first day of your last menstruation. And that is why we (obstetricians, gynecologists and general practitioners, even abroad) calculate with this date. Usually there are about 2 weeks between that date and your ovulation and thus fertilization. The growth of the fertilized egg into a full-term baby takes an average of 38 weeks. If you add the first 2 weeks to that, you arrive at 40 gestational weeks. So actually, you get the first 2 weeks fixed as a gift! To know for sure how far along you are, we make a term echo. We measure your baby and use this information to determine the due date.

Week 2: the fertilization

During this week, the actual fertilization takes place. Once a sperm cell enters the egg, the surface of the egg immediately changes. No other sperm cells can now enter. The invaded sperm cell loses its tail and fuses with the egg cell. From now on, the egg is called zygote.

Week 3: hormones are raging through your body

You really are pregnant now, though you don’t know it yet. Hormones are coursing through your body. Progesterone, for example, causes your cervical mucus to become impermeable again after ovulation. If you lose a little blood toward the end of the week, this could be an implantation bleed. During implantation, sometimes a small blood vessel can be damaged which causes this bleeding.

Week 4: germination leaf development

During this week, the so-called germination leaves develop. From this later all of your baby’s organs are formed.

  • Inside the clump of cells, next to the embryo, is a very small cavity with amniotic fluid.
  • Around the embryo and amniotic fluid is a membrane called the amnion.
  • Around this is a second membrane, the chorion.

When the baby is born, these 2 membranes will be together, but not yet. Now there are still fluid and a yolk sac between them. This yolk sac provides nutrition for the fetus, because the placenta has yet to develop.

Week 5: bean in your belly

The foetus is now about 2 millimeters in size and looks like a bean. Construction of the heart and central nervous system is already underway. An important hormone now is the hCG (human Chorionic Gonadotropin). It is produced right after implantation. The amount of hCG has now increased so much that your period stays away. On the first day of your absence you can already take a pregnancy test. If the test is positive and you are not yet taking folic acid, start taking it. Folic acid reduces the chance of having a baby with spina bifida or a heart defect. It is best if you already take the folic acid while you are trying to conceive. This ensures that you have enough folic acid in your body at least from the moment of conception (whenever that may be).

Week 6: grow, grow, grow

Your baby is now about 5 millimeters long. A lot is happening in this week. The head, chest and abdominal cavity are formed. But a primitive system of blood vessels is also being constructed, which will cause the heart to beat by the end of this week. The foundations for the stomach, intestines and lungs are also being laid now. Many women may experience all sorts of pregnancy signs (but they certainly shouldn’t) such as:

  • Frequent urination
  • Swollen breasts and sensitive nipples
  • A vague menstrual-like feeling at the bottom of your abdomen
  • Fatigue
  • Changed tastes

Week 7: development of organs and limbs

It is starting to become quite something. The construction of the spinal cord and brain is almost complete. By the end of this week, all organs are developed and the limbs are developing. Vaguely, hands and feet can already be recognized! What needs to happen now is for all organs to continue to grow and take their final place.

Week 8: the head

The head took its final shape. Relative to the body, it is very large, and will remain so for the next few weeks. The face is already starting to look like something. The eyes are on the side of the head, but are still covered with skin. There are already nostrils and the mouth, jaw and inner ear are developing.

Week 9: the first shocks

From millimeters your baby grows to centimeters, now 3 cm to be exact. The joints now begin to form and the baby begins to move a little. With little jolts, the arms and legs move slightly out of place. Unfortunately, you don’t feel any of this yet.

Week 10: folic acid

Your baby is about 4.5 cm long from crown to tailbone. The brain and spinal cord are fully constructed, which is why you may stop taking folic acid at the end of this week.

Week 11: the belly is growing

During this week, your baby is getting a skeleton of cartilage. Also, the testes or ovaries are formed. You may notice that your belly has already grown a little. Although it is often not yet visible to those around you. Due to the growth of your uterus, you may experience some bowel problems.

Week 12: Hooray! A milestone

Hooray! the first 12 weeks are over. The chances of anything going wrong now have decreased a lot. From now on, your baby is also no longer called embryo, but fetus. This week the nails develop, as well as the organ of smell and hearing. Vaguely, 2 auricles can already be seen. This makes it begin to look more like a real face. Until now, the intestines were for a small part in the umbilical cord, now they withdraw and come to lie more in the abdominal cavity.

Week 13: growing baby and uterus

Your baby is growing and your uterus is growing. The top of the uterus (fundus) is now at the level of your pubic bone (symphysis). The distance between the fundus and your symphysis can be used to measure whether the size of the baby matches the gestational age.

Week 14: Boy or girl?

Are you also so curious whether there is a boy or a girl in your belly? From this term you can see the gender of your baby with a sex determination ultrasound. From 14-15 weeks this is clearly visible. The face is finally finished, as the nose is also shaped. The baby can open and close his mouth and move his fingers independently. That means he can already start thumbing. You yourself can now start to notice that your belly is bulging a bit.

Week 15: growing and maturing

11 centimeters is your baby now. His limbs and organs are there. From now on, all the fetus has to do is grow and mature. This is very important, because even though your child is potentially ready, it cannot yet survive outside the womb. It is splashing around nicely in the amniotic fluid and this makes all its muscles stronger. It can now bend its arms and legs. It can swallow and move its upper lip. The latter is the start of the later sucking reflex. From now on, the baby swallows amniotic fluid regularly, and because its kidneys are already working, it also urinates small amounts.

Week 16: approximately 120 grams

From 11 cm, your baby has already grown to 15 cm. He now weighs about 120 grams. All the nutrients and oxygen the baby gets from the placenta. So he doesn’t have to breathe yet, but he is already beginning to practice that movement. The entire body is covered with very fine hairs, lanugo hairs. These hairs are released at the end of pregnancy. It then floats in the amniotic fluid and is swallowed by your baby. These hairs are part of the very first poop, the meconium. When your baby is born prematurely, the lanugo hairs are often still visible on the body.

Week 17: eye exercises

Your child now begins to do all kinds of eye exercises. He sometimes looks straight ahead, but can also squint very well now. Anything to be able to move his eyes properly later.

Week 18: light and dark

Are you also so curious how your baby looks now and how it is in your belly, make an appointment now for an extra ultrasound in 2D or 2D/3D/4D! You can have an extra ultrasound at any term in your pregnancy! These early ultrasounds allow you to see the baby in its entirety. Would you like to see your baby when it is a bit bigger, then plan an appointment for a deluxe 2D/3D/4D ultrasound! From now on, your baby begins to use his eyes and can distinguish light and dark. He has also grown rapidly again, 18 cm long and weighing 250 grams. During this week, a greasy substance forms on the skin. This protects the baby’s skin during the remaining months in your belly. This fatty substance is skin lubricant and is also called vernix. At the end of the pregnancy, this fat releases and small, white flakes float in the amniotic fluid. When your baby is born, you can often still see some of this skin grease in the skin folds.

Week 19: growing on for a while....

So in the beginning, the amniotic fluid is mainly produced by the placenta and the umbilical cord. It consists of water, salts, nutrients and waste products from the baby. Amniotic fluid has several functions. For example, it is a good buffer against the outside world and keeps the baby’s body temperature constant. Some women feel butterflies, plops or strange jolts in their lower abdomen around this time. This is the baby moving! If you don’t feel this yet, don’t worry. Many women don’t feel their baby until around the 20th week or even later.

Week 20: exercise

You are now 20 weeks pregnant and your baby is 25 cm long and weighs about 320 grams. He is beginning to move more and more, now about 200 times a day. The older he gets, the more he moves. However, much of the day he is still sleeping. So sometimes you won’t feel your baby move for a while, nor will you feel it every time the baby moves. The hearing begins to work. He may be startled by unexpected sounds, but also get used to certain sounds, such as your voice, or your dog’s bark. Around this time, the 20-week ultrasound can be done.

Week 21: gender of the baby

The sexual organs are now fully developed. On an ultrasound, the sex is visible from about 14-16 weeks. Your belly grows a lot at this time, probably the top of your uterus is now about the height of your navel.

Week 22: swimming lessons

Your baby is very mobile and swimming in all directions. He also frequently grabs the umbilical cord and squeezes it. This may all seem a bit scary, but it’s not. The vessels in the umbilical cord are protected by a jelly-like substance, which prevents the vessels from being pinched shut. Also, the umbilical cord is so long that your baby can easily move in all directions.

Week 23: subcutaneous fat

Until now, your baby has been a little on the skinny side, but that is about to change. As of now, subcutaneous fat is being produced, which will ensure that you will soon have a plump baby.

Week 24: about 500 grams

In the past 4 weeks, your baby has grown about 5 cm, making him now just over 30 cm long. Weight is also steadily increasing. He now weighs about 500 grams.

Week 25: lying down and kicking

Your baby has grown so big that he is no longer floating freely through the amniotic fluid. He begins to lie a bit against the wall of your uterus. He can still kick and turn quite a bit and has not yet assumed his final position either.

Week 26: Hooray! Another milestone.

26 weeks, another milestone reached. If your baby were born now, he is so far developed that there is a good chance he could survive outside the womb. Whether the baby will make it depends, among other things, on its weight and possible complications during pregnancy or delivery. Such a small child has virtually no resistance to infection and is still very vulnerable. Also, the lungs are not yet fully mature. In special neonatal centers, the situation in your belly is imitated as much as possible with warm incubators. But in your belly, of course, your baby has it much better.

Week 27: rhesusD factor and anti-D injection

Blood type – Rhesus D factor If you have a rhesus negative blood type, your blood will be tested for rhesus antibodies this week. If you are rhesus negative and your child is rhesus positive, you will be given an injection of antirhesus D immunoglobulin. This ensures that you yourself will not produce antibodies that can make your baby sick. After delivery, you will get another injection of this same anti-rhesus D immunoglobulin. Chances are that when you come to our midwife’s checkup now, she can feel how your baby is lying. Head and buttocks are often easy to distinguish.

Heart listening Your partner can try listening to the heart with an empty toilet roll from now on. To do this, you lie on your back. Your partner puts the toilet roll on your belly and presses it firmly against your belly with his ear. He should not hold the roll with his hands, because then you will no longer hear it well. The best place to listen to the heart is on the lower left or right side, between pubic bone and navel. Good luck!

Week 28: boy or girl

There is now slowly beginning to be a difference between boys and girls. In fact, boys are on average slightly heavier at birth. That means a boy now weighs about 1000 grams. While a girl now weighs about 897 grams. These numbers only apply to a first pregnancy. If you are pregnant for a 2nd, 3rd or maybe even 4th time, your baby is probably a little heavier by now.

Week 29: Your baby's skin

The skin was still very red until now, but it is now becoming redder. This is because more subcutaneous fat is being built up. Also, the lanugo hairs slowly begin to disappear.

Week 30: Your baby is already 40 cm!

Your baby is now about 40 cm long and weighs between 1200 and 1300 grams.

 

Week 31: pair diving

Your baby’s freedom of movement is now somewhat restricted. He is getting bigger and therefore has to make more effort to mate. It can still do it, but you can feel it considerably.

Week 32: the hiccups

Has your baby had hiccups before? From now on, your baby may experience it more and more often. Hiccups are felt as a regular jolt that can last quite a while. Hiccups are caused by the baby drinking from the amniotic fluid. If its stomach is too full, the contents may irritate the diaphragm in such a way as to cause a reflex. After a while it goes away by itself.

Week 33 & 34: the first bowel movement

The lanugo hairs and vernix continue to let go.

As your baby swallows the amniotic fluid, he gets this in. It stimulates the intestines, which is good. The intestines must start working properly soon after delivery. Within 24 hours your baby will poop once. This poop is black-green, doesn’t smell and is incredibly sticky, meconium.

Week 35: final position

Your baby is now about 43 cm long and weighs about 23-2400 grams. During this week, he will take his final position. He is supposed to lie with his head down. Your baby may also be lying with his head up, a so-called breech presentation. Or maybe he is lying transverse. In these cases, an attempt may be made to turn the baby around through a version.

Week 36: indentation

If you are pregnant for the first time, your baby will begin to descend around this time. This indentation is because your baby is now getting so big that he is going to use all the space and therefore he sinks deeper into your pelvis. If the head has not yet descended and the waters break, you lie down to prevent the umbilical cord from dropping, you also call the midwife immediately. She will then come and see you. If the head has descended, you may continue to walk around if your waters have broken. When you have given birth before, it is not necessary for the head to descend. However, you should lie down and call if your waters break.

Week 37: big and strong enough

Once this week is over, you may go into labor without having to go to the hospital. Your baby is really all finished, he is basically big and strong enough to do everything by himself.

Week 38: your baby is now officially full-term

He is about 48 cm long and weighs between 3000 and 3100 grams on average. Boys are slightly heavier than girls. The due date is only 3 weeks away, but the due date starts now and ends at 42 weeks. So your baby has 5 weeks to come. Very few children are born on the actual due date.

Week 39: growing like cabbage

There is little room left in your belly. That’s why these last few weeks you feel mostly prodding from elbows and knees. What he is still doing now is growing, sometimes up to 200 grams a week!

Week 40: ready for delivery

For the last few weeks, your baby has been all huddled up in your belly. He now weighs about 3,400 grams and is ready for delivery.

Week 41 & 42: not born yet?

Your due date has passed but your baby has not yet been born. This is an exciting time. When will it happen? If your baby is born now, you can usually tell by looking at him or her that he is a little later. He will have almost no more skin lubrication in the skin folds and the lanugo hairs have also disappeared. The little skin may even look quite dry. During this period it is important that you continue to feel your baby moving well in your belly. When this becomes noticeably less, you should let the midwife know. Now it is really waiting for the delivery. If your baby has not been born by the end of the 42nd week, an appointment will be made to induce. The labor will then be induced to prevent your baby from staying in labor too long.

The birth

Week 1

Usually there are about 2 weeks between that date and your ovulation and thus fertilization. The growth of the fertilized egg into a full-term baby takes an average of 38 weeks. If you add the first 2 weeks to that, you arrive at 40 gestational weeks. So actually, you get the first 2 weeks fixed as a gift! To know for sure how far along you are, we make a term echo. We measure your baby and use this information to determine the due date.

Week 2

Your egg has matured and is ready for fertilization. Coincidence further ensures what your baby will look like and what kind of character it will have. These traits are created by the combination of genes from the egg and sperm cells:

  • All of our hereditary traits are on our genes. They are on the chromosomes (rod-shaped pieces of protein) in every cell of our body.
  • Each cell has 46 chromosomes, 23 pairs. Only the egg and sperm cell have only half. Therefore, it is possible to make a new human being from these 2 halves. For this, the egg cell provides one half and the sperm cell the other. The 23rd pair of chromosomes determines the sex of the baby. The sperm determines whether it will be a boy or girl.
  • The 23rd pair in the woman is XX, and therefore the woman always passes an X in her egg. The 23rd pair in the male consists of XY. A sperm cell can therefore contain either an X or a Y. If the egg is fertilized with an X, it will be a girl. If the egg is fertilized with a Y, it will be a boy.

Week 3

For the first 24 hours after fertilization, nothing happens for a while. Only then does the egg begin to divide, creating a tangle of cells that keeps expanding. Fertilization has taken place in one of the fallopian tubes, and now tiny cilia cause the fertilized egg to be transported to the uterus. It is only a small piece, but it takes about 5-7 days for the egg to arrive in the uterus. There, the cells attach to the uterine wall. The outer cells will later develop into placenta. Once the embryo is implanted, it is called an embryo.

Week 5: Mothers for Mothers

The hCG hormone is in your urine, which allows the test to determine if you are pregnant. The hCG can help people with fertility problems get pregnant, too. The organization Mothers for Mothers collects urine from pregnant women for this purpose. The urine is collected until the 16th week of pregnancy. If you want, you can participate in this collection starting now. You can sign up at www.MoedersvoorMoeders.nl.