33 weeks pregnant
Your baby's brain is fully developed.
In short
At 33 weeks your baby is about the size of a pineapple, around 44.0 cm long and 2.1 kg. Your baby's brain is fully developed.
- Third trimester, week 33 of about 40.
- If you haven't had the whooping cough vaccine yet, ask your GP soon. It's recommended before 36 weeks and may be less effective after that.
Turn your baby round in 3D every week in the free Lullagram pregnancy section
Your baby's brain and nervous system are now fully developed. Bones keep hardening, but the skull bones stay soft so they can slide over each other during birth.
How big is my baby at 33 weeks?
At 33 weeks your baby is about the size of a pineapple, around 44.0 cm long and 2.1 kg. Before about 14 weeks babies are measured from crown to rump; after that the figure is head to heel. These are typical figures from fetal growth charts. Your own baby may be bigger or smaller, and your scans are what count.
What is my baby doing at 33 weeks?
- Your baby's brain and nervous system are now fully developed.
- Bones keep hardening, but the skull bones stay soft so they can slide over each other during birth.
- Taste buds are well developed and what you eat may shape the flavours your baby likes.
- Your baby is curled up with legs bent towards the chest but still has room to move.
What changes for me at 33 weeks pregnant?
- Braxton Hicks tightenings may become more noticeable.
- They usually last less than a minute, come and go without a pattern and don't get stronger.
- Feeling more tired and uncomfortable is common in these final weeks.
- Your baby should keep moving as before, so contact your maternity unit straight away if movements slow down, change or stop.
What is a good tip for this week?
Start gathering things for your hospital bag, including your pregnancy notes, comfortable nightwear, maternity pads and newborn nappies.
What can a partner do this week?
Pack a small bag of your own too, with snacks, a phone charger and a change of clothes.
What should I know in Ireland at 33 weeks?
- If you haven't had the whooping cough vaccine yet, ask your GP soon. It's recommended before 36 weeks and may be less effective after that.
When to get help: Before 37 weeks, go to your maternity unit straight away if you have regular contractions that are getting stronger, a gush or trickle of fluid, bleeding or period-type pains. HSE: when to get help.
Want these updates on your phone? The Lullagram app has a free pregnancy section with this week-by-week guide, Irish dates worked out from your due date, a contraction timer and more. When your baby arrives, the baby tracker is ready in the same app.
Guides for your pregnancy: pregnancy care in Ireland · maternity leave and benefit · hospital bag checklist · popular baby names · free IVF in Ireland · due date calculator
Sources and guidance
This page is written to be consistent with the official guidance below. It is general information for parents in Ireland, not medical advice. Links checked 23 September 2026.
High Quality app that helped with the sleepless nights. Must have for new parents.