31 Weeks Pregnant
You’re 31 weeks pregnant — in the third trimester, and 9 weeks to go until your due date. Your baby is about the size of a coconut this week.
How big is your baby at 31 weeks?
Size of a
coconut
Length
~41.1 cm
Weight
~1502 g
Last week your baby was about the size of a cabbage; this week it's grown to roughly a coconut.
Sizes are averages from standard fetal-growth references. Every baby grows at its own pace — your provider tracks yours at scans.
Baby development at week 31
The brain is developing rapidly, now able to process information from all five senses. The fetus can turn its head from side to side and is making breathing movements, though the lungs aren't finished. All major organs except the lungs are now fully functional. Most of the remaining work is putting on weight. About the size of a coconut.
Your body at 31 weeks
Common symptoms many people notice around week 31 include:
- Leaking colostrum (early breast milk) for some
- Backache
- Frequent urination as the baby presses on the bladder
- Braxton Hicks contractions
Symptoms vary enormously from person to person and pregnancy to pregnancy. Not having a symptom on this list is just as normal as having it.
Tips for week 31
- Breast pads can help if colostrum leaks
- Support your lower back when sitting and standing
- Consider finalising your birth plan
What trimester is 31 weeks?
Week 31 falls in the third trimester. As a quick map: the first trimester runs weeks 1–13, the second covers weeks 14–27, and the third is week 28 through birth (a due date is set at 40 weeks). Want your own dates? Our Pregnancy Due Date Calculator shows your due date and exactly how far along you are today.
The third trimester (weeks 28–40+) is about growth and getting ready for birth. Prenatal visits become more frequent, the baby gains most of its weight, and you'll watch for the signs of labour. Tiredness and physical discomfort tend to return as the due date approaches.
Frequently asked questions
- How many months is 31 weeks pregnant?
- 31 weeks pregnant is about 8 months. Pregnancy months don't divide evenly into 4-week blocks, so week-to-month conversions are approximate — most providers track pregnancy by week, not month.
- How big is the baby at 31 weeks?
- At 31 weeks, the baby is about the size of a coconut, roughly 41.1 cm and around 1502 g. These are averages — healthy babies vary, and your provider tracks your baby's own growth curve at scans.
- What trimester is 31 weeks?
- Week 31 is in the third trimester. The first trimester is weeks 1–13, the second is weeks 14–27, and the third is weeks 28 to birth (around week 40).