Stages Of Foetal Development

Stages Of Foetal Development

4 Aug 2022 | 6 min Read

Sayani Basu

Author | 607 Articles

Foetal development from a single cell organism to a baby is a miraculous process that begins soon after conception. Understanding foetal development month by month is vital for understanding a baby’s health, which is assessed by the doctor using a foetal growth chart.

Are you curious to know its stages of development? Scroll through to know the stages of foetal development and find out how your baby grows and develops during the nine months.

Your Baby’s Growth: Conception To Birth

Do you know about the several foetal development stages? From conception to labour, your baby in the womb is growing and developing. The unborn baby moves through different stages. It starts as a blastocyst, matures into an embryo, and then into a foetus.

Around the fifth week mark, your baby’s heart will begin to beat and you will come to know everything about foetal heart rate from your doctor. Between 18 to 24 weeks, you can feel the baby movement in pregnancy.

At 27 weeks, the developing baby will have regular sleep and wake cycles, and at 39 weeks, they will be physically developed.


Conception or fertilisation happens when a sperm meets and penetrates an egg. Now, the genetic makeup is complete, including the sex of the baby. 

About three days after conception, the fertilized egg gets divided fast into several cells. It also passes through the fallopian tube into the uterus and attaches to the uterine wall. This is the stage when the placenta that nourishes the baby, starts to form. Here’s everything about the baby’s position month by month and the stages of foetal development by week.

Foetal Development Week By Week Real Pictures

Every pregnant couple is so excited about foetal development. The first week of pregnancy starts with the first day of the woman’s menstrual period and she is not yet pregnant.

At the end of the second week, an egg is released from her ovary. This is when the woman is most likely to conceive if she has had unprotected intercourse.

Here’s a peek into the stages of stages of a foetus and foetal development – pregnancy week by week.

Development At 4 Weeks

  • At this point, the embryo is about 1/6-inches.
  • The baby is developing the structures that will eventually form the unborn’s face and neck.
  • The heart and blood vessels also develop at this stage.
  • The structures that will form arms and legs (limb buds) begin to appear.
  • The brain develops into five areas and some of the cranial nerves are prominent.

Development At 8 Weeks

How does a real foetus look like at 8 weeks? How big is a fetus at 8 weeks?

  • The foetus is now about 11/4-inches long, and the head makes up about half this size.
  • The beginnings of all the key body parts are present even though they are not completely positioned in their final locations.
  • The eyelids and ears have started to form, and the tip of the nose is also visible.

Development At 12 Weeks

How does the actual 12 week foetus look like? What does a foetus look like at 12 weeks?

  • At this stage, the baby measures about two inches and starts to make its own movements.
  • You might start to feel the top of your uterus above your pubic bone.
  • Your doctor might hear the baby’s heartbeat with special instruments.
  • The sex organs of the unborn start to become prominent.

Development At 16 Weeks

  • The baby now measures about 4.3 to 4.6 inches and weighs about 0.09 kg (3.5 ounces).
  • You are able to feel the top of your uterus about three inches below your belly button.
  • The baby’s eyes can blink and the heart and blood vessels have fully formed.
  • The baby’s fingers and toes have fingerprints, muscle tissue and bones continue to develop, and the bones become harder.
  • The liver and pancreas now produce secretions.

Development At 20 Weeks

What does a 20 week foetus look like?

  • At this stage, the baby weighs about 0.28 kg (10 ounces) and is a little more than 6 inches long.
  • Your uterus will be now at the level of your belly button.
  • The baby in the womb can suck a thumb, yawn, stretch, and make faces.

Time For An Ultrasound

  • An ultrasound is generally done at 20 weeks of pregnancy.
  • During an ultrasound scan, you can see listen to the baby’s heartbeat and see the movement of its arms, and legs on the ultrasound.

Development At 24 Weeks

  • At this point, the baby weighs about 0.63 kg (1.4 pounds) and responds to sounds by moving or increasing their pulse.
  • You might also notice jerking motions if they hiccup.
  • With the inner ear being fully developed, the baby might be able to sense being upside down in the womb.
stages of foetal development
Image of the foetus at month 7. | Image Source: WebMD

Development At 28 Weeks

  • The baby now weighs about 0.90 kg (2 pounds) and changes its position often at this stage of pregnancy.
  • The nervous system is also developed and controls some body functions of the baby.
  • While immature, the respiratory system produces surfactant and helps the air sacs fill with air.
  • If you have to deliver prematurely, there’s a good chance that the baby will survive.

It is advisable to ask your doctor about preterm labour warning signs now.

foetal development stages
Image of the foetus at month 8. | Image Source: WebMD

Development At 32 Weeks

  • At this stage, the baby weighs almost 1.81 kg (4 pounds) and is moving around often.
  • A layer of fat starts to form under the skin. Hence, the unborn’s skin has less wrinkles.
  • The bones have developed fully and the body begins storing minerals like iron, calcium, and phosphorus.
baby in womb
Image of the foetus at month 9. | Image Source: WebMD

Development At 36 Weeks

  • At this point, the size of the babies vary and depends on many factors, such as gender and the number of babies being carried.
  • On average, a baby 36 weeks of pregnancy is about 18.5 inches and weighs close to 2.72 kg (6 pounds).
  • The brain has been rapidly developing and the lungs are almost fully developed.
  • Your baby’s head is generally positioned down into the pelvis by now and is considered at ‘term’ when it’s 37 weeks.

Birth Time!

Now, it’s the birth time! Now that you know all about pregnancy anatomy month by month, you should also know how is the due date calculated?

An expecting mum’s due date marks the end of their 40th week of pregnancy. Plus, the delivery date is calculated using the first day of the woman’s last period. Based on this, a pregnancy can last between 38 and 42 weeks, with a full-term delivery slated around 40 weeks.

We hope that the information on stages of pregnancy month by month doubles your excitement.

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