Stages Of Fetal Development

Stages Of Fetal Development - The Third Trimester

The third trimester in the stages of fetal development is nearly all about getting bigger! You will notice this now too. As your baby continues to get bigger, you will need to take things easy.

Seeing as most of the major organs are now formed, weekly fetal development will now be spent getting bigger, creating more fat, and waiting for organs to mature enough for your baby to be born.

Ok here's your detailed view of the stages of fetal development for the last 3 months. Sit back and wonder with amazement at what started out as one egg - and one sperm!

Stages of fetal development - Weeks 27 to 30

Fetus development at this stage includes lots more growing!

Week 27

Your baby will now weigh in at around 1kg (2 and a half pounds) and measure around 26cms from crown to rump.
The protective covers have fallen away from your baby's eyes now, so he can open and close them. He may now be practising blinking.
Your baby's brain is continuing to grow, and the numbers of connections from the brain to the nerve endings are also continually being made.
Your baby will be starting to get quite cramped inside your uterus. His kicks will be feeling stronger as he no longer has the room to move around as before.

Week 28

Your baby has even less free space inside your uterus than he did last week. So over the next few weeks he may start to settle into the head down position ready for birth.

Week 29

Your baby is now breathing the way we do! Special fluid in your uterus will protect his delicate lungs.
Your baby's skin will be starting to look less wrinkled now as he continues to build fat underneath it.
He may now be 3lb in weight (1.5kg) The size of his head is now in the correct proportion to the rest of his limbs.

Week 30

Your baby may be aware that you are having Braxton Hicks contractions (these are a practice run for the real thing) Even if you can't feel them happening.
He is still covered in vernix, this will continue to protect his skin. His skin will now be a healthy pink colour.

Stages of fetal development - Weeks 31 to 34

You will notice now that the stages of fetal development aren't as complicated as before. But they are still just as important. Every week spent inside your uterus gives your baby a better chance of survival if he is born prematurely.

Week 31

Your baby may have a full head of hair by now!
You baby may now be settled down into a position ready for the impending birth. If he is lying upside down, his head will settle into your pelvis.
He now weighs a whopping 4 to 5 pounds, and may be as long as 30cm from crown to rump! No wonder he can't move around a lot anymore!

Week 32

Your baby is now fully formed!
He will measure around 42cm.
Although baby's lungs are breathing amniotic fluid, he still can't breath unassisted as of yet.
Your baby will continue to build up fat to help regulate his temperature when he's born.

Week 33

You might notice little jerky movements if your baby swallows too much amniotic fluid and gets the hiccups!
Your baby can't move around too much now as space really is tight in there.
If your baby is a boy, then his testicles will start to descend from his abdomen down into the scrotum.

Week 34

Your baby's face will have a much smoother and rounded look to it now as he continues to build fat under the skin.
His legs may be tightly tucked under his body as he is curled tightly in your uterus
Your baby will be opening and closing his eyes for sleep now, just like a newborn!

Stages of fetal development - Weeks 35 - 40

This is the last month in the stages of fetal development, put your feet up and relax while your baby continues to get bigger!

Week 35

Antibodies are passed to your baby via the placenta.
Your baby may now weigh around 5 to 5 and a half pounds (2.5kg)
If you shine a light on your tummy, your baby will see a red glow!

Week 36

Your baby's lungs are still maturing.
Your babies intestines will be filled with meconium, this is like a black sticky substance that your baby will expel as his first 'poo' after his birth. This sometimes happens before the birth, your midwife will watch carefully to see if baby has inhaled any during the birth. Your midwife will sort this out with a special sucking tool that will clear baby's airways.

Week 37

Your baby will put on weight at an astounding rate for these last couple of weeks. He can now gain up to an ounce a day!
Your baby is curled up in uterus really tight, he has make the most of his confined space.
Your baby is now classed as 'full term'.

Week 38

The skin on your baby's hands and feet may be quite wrinkled now - Imagine how you would look after 9 months in the bath tub!
Your baby's head may measure around the same size as his abdomen! (strange fact!)

Week 39

The lanugo (fine hairs) on baby's skin may now be gone, you may find a little still there when he's born.
Your baby's lungs are still maturing and the surfactant production continues.
Baby may now be practising the 'rooting' reflex, where he turns his head from side to side while his mouth suckles.
He may now weigh around 7lbs.

Week 40

The longer your baby is in there now, the bigger he will get. There's not much more for him to do!
The vernix may now have vanished. Don't worry if it hasn't this can help to protect and moisturise your baby's skin after he is born.

And that's it for the weekly fetal development of the third trimester... Congratulations! Your baby should be here now, or if not then very soon!

I hope you enjoyed finding out the week by week fetal development stages of your baby, it's been a long journey. Probably full of emotional ups and downs, all that is left now is for you to enjoy motherhood!

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