🤰 Third trimester
31 weeks pregnant
Your baby is about the size of a coconut
By Emma Whitfield · Pregnancy & Baby Writer
Your baby at 31 weeks
The baby can now process information from all five senses. They're practising breathing movements and may settle into a head-down position, though many still turn.
Your body at 31 weeks
You may leak more colostrum and feel Braxton Hicks more often. Backache and pelvic pressure increase. Fatigue and "nesting" urges can both appear.
Common symptoms this week
- More colostrum leaks
- Pelvic pressure
- Nesting urges
- Fatigue
Symptom lists are typical, never exhaustive — and having none of them is normal too.
Focus this week
Wash and sort baby clothes and bedding in non-bio detergent, and set up the car seat so you can practise fitting it before the birth.
Week 31 checklist
- Attend the 31-week appointment if it's your first baby
- Wash baby clothes and bedding in non-bio detergent
- Fit the car seat once and practise — don't leave it until week 39
31 weeks pregnant: common questions
Should I buy newborn or 0–3 month clothes?
Mostly 0–3 months, with a few newborn-size items as backup — newborn sizing runs small and many babies outgrow it in a fortnight, if they fit it at all. Five to seven sleepsuits and vests per size covers the reality of several changes a day.
How big is my baby at 31 weeks pregnant?
At 31 weeks, your baby is approximately the size of a coconut, about 41.1cm and around 1500g. These are approximate averages — every baby grows at its own pace.
What's happening at 31 weeks pregnant?
The baby can now process information from all five senses. They're practising breathing movements and may settle into a head-down position, though many still turn. For you: you may leak more colostrum and feel braxton hicks more often. backache and pelvic pressure increase. fatigue and "nesting" urges can both appear.
Which trimester is 31 weeks?
31 weeks pregnant is in the third trimester. The first trimester runs to the end of week 12, the second from weeks 13 to 26, and the third from week 27 to birth.
Sources & further reading
This is general information, not medical advice — every pregnancy is different. For anything that worries you, and for all your antenatal care, speak to your midwife or GP. If your baby's movements ever slow down or change, contact your maternity unit immediately, day or night. Reviewed July 2026.