39 Weeks Pregnant
You’re 39 weeks pregnant — in the third trimester, and 1 week to go until your due date. Your baby is about the size of a mini watermelon this week.
★ Full term — all organs ready.
How big is your baby at 39 weeks?
Size of a
mini watermelon
Length
~50.7 cm
Weight
~3288 g
Last week your baby was about the size of a leek; this week it's grown to roughly a mini watermelon.
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 39
The baby is now 'full term'. All organs are developed and ready to function outside the womb. The baby is still building a layer of fat to control body temperature, and the head may have settled deep into the pelvis ready for birth. The umbilical cord is delivering antibodies that will protect the newborn. About the size of a mini watermelon.
Your body at 39 weeks
Common symptoms many people notice around week 39 include:
- Strong, possibly regular contractions as labour nears
- Pelvic pressure and backache
- Loss of mucus plug or bloody show
- Nesting energy or exhaustion
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 39
- Time contractions — regular and intensifying means labour may be starting
- Call your provider when contractions follow the guidance you've been given
- Stay calm; first labours often build gradually
What trimester is 39 weeks?
Week 39 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 39 weeks pregnant?
- 39 weeks pregnant is about 9 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 39 weeks?
- At 39 weeks, the baby is about the size of a mini watermelon, roughly 50.7 cm and around 3288 g. These are averages — healthy babies vary, and your provider tracks your baby's own growth curve at scans.
- What trimester is 39 weeks?
- Week 39 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).