At 39 weeks pregnant you are in the third trimester, with about 1 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 9 of pregnancy.
How big is your baby at 39 weeks?
Around week 39, your baby is often compared to a mini watermelon. 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 39 weeks is about 3.19 kg. Most healthy babies fall between roughly 2.37 kg and 4.03 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 39 weeks
Full term. Many people feel tired, impatient and ready. Call your doctor if you think labour has started.
What is going on
Full term. Your body is ready, and you may feel a mix of impatience, tiredness and excitement. Regular contractions that get stronger and closer are a sign of labour.
What can help
Call your doctor if your water breaks, contractions become regular, bleeding appears or your baby moves less.
Other weeks
37 weeks pregnant · 38 weeks pregnant · 40 weeks pregnant
See all weeks on the pregnancy week by week page, or try the interactive week-by-week guide.