Baby’s development in the third trimester

Learn about how your baby’s brain develops and changes each month in the third trimester.

Month 7:

  • Baby has proper hearing and can open their eyes.
  • Baby starts to know voices they hear the most. The more mum and dad talk and sing to baby before birth, the more baby learns who they are.

Month 8:

  • The coordination part of the brain grows fast. This means baby can now blink, close eyes, turn their head and clutch.

Month 9:

  • Baby’s lungs have finished growing – ready to start breathing soon.
  • Baby may move less now because there isn’t much room.
  • Baby’s head is about the size of a grapefruit (around 12.7cm). This shows how much baby’s brain has grown.
  • The brain weighs almost as much as a tin of tomato soup (around 300 grams).
  • Baby is about as long as a bunch of celery (around 51cm).
  • Baby is ready to come out and connect to Country!

There are people you can chat to about your growing bub during pregnancy and after they’re born. Visit your local Early Years Place.

Published — 20 February 2019 Last updated — 11 March 2019

Want personalised tips and activities?

Complete these short questions to get personalised tips and activities to see how simple and easy it can be.

Get started
01 / 05

What is your relationship with the child?


What best describes your location?


If you had a spare moment, what would you most likely do with the child?


And finally…

Do you speak another language at home apart from English?
Are you of Aboriginal and / or Torres Strait Islander descent?
Does the child need additional support with their development or learning?
Now we know a little more about the content that might interest you we’ve compiled it into a handy page for you.