12 weeks pregnant
All the parts are in place.
In short
At 12 weeks your baby is about the size of a satsuma, around 5.4 cm long. All the parts are in place.
- First trimester, week 12 of about 40.
- At work, you're entitled to paid time off for antenatal appointments. Give your employer a doctor's note confirming the pregnancy and at least 2 weeks' notice of each appointment.
All your baby's organs, muscles, limbs and bones are now in place. The skeleton is starting to change from soft cartilage into hard bone.
How big is my baby at 12 weeks?
At 12 weeks your baby is about the size of a satsuma, around 5.4 cm long. 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 12 weeks?
- All your baby's organs, muscles, limbs and bones are now in place.
- The skeleton is starting to change from soft cartilage into hard bone.
- Your baby is moving quite a lot, even though it's too early for you to feel it.
- Your baby can already suck their thumb.
What changes for me at 12 weeks pregnant?
- This is the last week of your first trimester.
- For many, nausea and tiredness start to ease around now, though for some it lasts until 16 to 20 weeks.
- Your waist may be thickening and your breasts getting bigger.
What is a good tip for this week?
There's no need to eat for two. Regular, balanced meals with plenty of fruit and vegetables are enough.
What can a partner do this week?
Talk together about when and how you'd like to share your news, as there's no right or wrong time.
What should I know in Ireland at 12 weeks?
- At work, you're entitled to paid time off for antenatal appointments. Give your employer a doctor's note confirming the pregnancy and at least 2 weeks' notice of each appointment.
When to get help: Contact your midwife, GP or maternity unit straight away if you have bleeding from your vagina or severe tummy pain. 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.
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.