How's my baby doing?

How's my baby doing

Keeping track of how your little one develops from week to week is one of the wonderful things about pregnancy because everything changes so much. From conception, it takes on average, 40 weeks to grow a baby inside you. Here are some snapshots of how your baby might be looking at various stages:

Week 4

Just 4 weeks after conception, your baby’s eyes and ears are developing fast, as is a tiny beating heart.

Week 8

By the end of the 8th week, your baby will have grown to about 3cm and weigh about 3g (that's less than a teaspoonful of sugar!). Their brain will already be alert and active.

Week 12

At 12 weeks, your baby weighs about 15g and is around 6cm long (babies in the womb are usually measured from the top of the head - the ‘crown' - to the rump, rather than from head to toe).

You might not have a bump or be able to feel your baby yet, but your baby’s already moving and waving their arms and legs. Little foreheads have been known to wrinkle and lips twitch. There’s even a bit of thumb-sucking going on!

Week 16

By 16 weeks your baby is already almost completely developed. They can sense light and tell the difference between bitter and sweet substances in your amniotic fluid.

Week 20

Half way there and your baby will now be about 16cm long and weighing only about 340g. In the next four weeks, overall weight is doubled. Eyes will open and close and the first teeth will have formed within the gums. Babies born after 24 weeks may stand a chance of surviving outside the womb.

Your baby will be responsive to external stimulation, like the soothing sounds of conversation or music.

Week 29

A time of rapid growth, your baby at 29 weeks is likely to be around 26cm long and weigh 1.1kg. The limbs are starting to fill out and lungs are maturing quickly. Your baby can recognise your voice now and has developed a sleeping and waking pattern.

Week 34

By 34 weeks, your baby's lungs are still maturing. They can sense changes in light through your tummy, and can also recognise your voice and your partner’s too. Your baby's immune system is developing and you might notice the occasional hiccup!

Week 40

37-42 weeks is considered full term but normally only around 5% of babies arrive on their given due date. Your little baby is ready to meet the world! Even tiny finger and toenails are fully formed.

Your baby will be practising sucking and swallowing, blinking, grasping and breathing. And although their movements may change, you should still notice at least 10 in 10 hours. You're almost there!

Pregnancy calendar

For a more detailed, week-by-week guide to your pregnancy, including the development of your growing baby.
Take a look at our pregnancy calendar.

  • Print page
  • Back to top

Have you got a question?

If you want more advice, please ask a question or visit our forum.

Otherwise, please get in touch with the HiPP Baby Club.