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Pregnancy week by week

38 weeks pregnant

Your baby is getting into position.

In short

At 38 weeks your baby is about the size of a bag of potatoes, around 49.2 cm long and 3.19 kg. Your baby is getting into position.

  • Third trimester, week 38 of about 40.
  • Your maternity leave must start at least 2 weeks before the end of the week your baby is due, so it begins by around now if you're still working.
About the size ofBag of potatoes
Length, head to heel49.2 cm
Typical weight3.19 kg

Your baby's heart and circulation are fully formed. In these last weeks your baby's head should move down into your pelvis, though sometimes this only happens once labour starts.

How big is my baby at 38 weeks?

At 38 weeks your baby is about the size of a bag of potatoes, around 49.2 cm long and 3.19 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 38 weeks?

What changes for me at 38 weeks pregnant?

What is a good tip for this week?

Time 3 contractions in a row with your phone or a watch. Call your midwife or maternity unit when they are regular, last at least 60 seconds and come every 5 minutes.

What can a partner do this week?

Learn how to time contractions so you can keep track when labour starts.

What should I know in Ireland at 38 weeks?

When to get help: Phone your maternity unit and go in if your contractions are 5 minutes apart and getting stronger, your waters break, you have bleeding or your baby's movements change. 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.