At 31 weeks pregnant you are in the third trimester, with about 9 weeks to go until a 40-week due date. Weeks are counted from the first day of your last period, so this is roughly month 8 of pregnancy.
How big is your baby at 31 weeks?
Around week 31, your baby is often compared to a coconut. Fruit and vegetable comparisons are a friendly way to picture the size, not an exact measurement.
From the INTERGROWTH-21st international standard (University of Oxford), the median estimated fetal weight at 31 weeks is about 1.57 kg. Most healthy babies fall between roughly 1.21 kg and 2.05 kg (about the 2nd to 98th percentile). Scan estimates carry some margin of error, so a number on its own is rarely a reason to worry. Our guide on reading the weight on your scan report explains more, and the baby weight checker lets you enter your own report.
The third trimester runs from week 28 until birth. The baby gains most of its weight now, and your body prepares for labour.
Your body at 31 weeks
Braxton Hicks tightenings may be more frequent. Piles and constipation can bother you.
What is going on
The womb practises contracting. These Braxton Hicks tightenings are usually painless and irregular, and they ease when you change position or drink water.
What can help
Rest and drink water. If tightenings become regular or painful, call your doctor.
Other weeks
29 weeks pregnant · 30 weeks pregnant · 32 weeks pregnant · 33 weeks pregnant
See all weeks on the pregnancy week by week page, or try the interactive week-by-week guide.