31 of 40 weeks
Baby size this week
As lovely as a pineapple
Measurements are averages — every baby grows at their own pace.
Length 41.1 cm 16.2 in
Weight 1.50 kg 3 lb 5 oz
Your baby this week
- All five senses are functional
- Your baby turns her head from side to side
- Rapid weight gain begins — about 250 g a week
- The uterus gets crowded, so moves feel sharper
Your body this week
Heartburn
Swelling
Insomnia
Braxton Hicks
This week's to-do
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How we measure week 31
Pregnancy weeks are counted from the first day of your last menstrual period, following standard ACOG and NHS guidance. Sizes are crown-rump length in early weeks and head-to-heel from around week 20. Your care team may adjust dates after an ultrasound.
BumpCount offers general information and does not replace advice from your doctor or midwife.