Pregnancy › Week by Week › Week 39
At 39 weeks your baby is about the size of a mini watermelon. You have officially reached full term, the window medicine considers the best time for a baby to be born.
Size
A mini watermelon
head to heel
Length
20.0 in
about 50.7 cm
Weight
7.25 lb
about 3290 g
Your baby at 39 weeks
Full term and finishing the last details, mostly the brain, the lungs, and a final layer of fat.
Reaching 39 weeks is a real marker. This is the start of full term, which runs from 39 weeks 0 days to 40 weeks 6 days, and research shows babies born in this window tend to have the smoothest starts. Your baby is ready, with just a few finishing touches underway.
Brain and lungs. These two are the last to fully mature, and they keep developing right up to birth and beyond. It is one reason those final weeks matter, and why 39 weeks is considered such a good place to be.
Fat and skin. Your baby is still adding a final layer of fat that helps with warmth and steady blood sugar after birth. The skin has shifted from the earlier reddish tone to a pink-white, and it looks smooth and full.
Ready to go. The reflexes for feeding are in place, the grip is strong, and your baby is tucked low and usually head down, simply waiting for labor to begin. Little changes now beyond continued weight gain.
How big is your baby at 39 weeks?
About 20 inches (50.7 cm) head to heel and roughly 7.25 pounds (3.3 kg).
Your baby is measured head to heel and keeps gaining a little fat each day. Space is tight, so movements feel like firm rolls, wriggles, and pushes rather than sharp kicks, but they should still be regular. Keep counting them and call your provider the same day if the pattern drops, this stays important right up to birth.
Your body at 39 weeks
Heavy, low, and waiting. Your body is quietly getting ready, even on the days nothing seems to happen.
The pelvic pressure is strong now as your baby sits low, and you may notice more of the small signs that the body is preparing: a bit of bloody show as the cervix softens, looser stools, a burst of nesting energy, and Braxton Hicks that can feel closer to the real thing. None of these tells you exactly when labor will start, and it is normal to have them for days.
Sleep is often broken by pressure, trips to the bathroom, and a busy mind, so rest whenever you can, day or night. If you are watching for the signs that labor is truly starting, our labor and birth guide walks through what to look for, and week 36 covers how to tell practice contractions from the real thing.
What is normal, and when to call your provider
Bloody show and practice contractions are normal now, but call your provider or go in for any of these:
- A clear drop in your baby’s movements, or a stretch without the usual pattern, call the same day
- A gush or a steady leak of fluid, which can mean your water has broken
- Any bright red vaginal bleeding, which is different from the pink-tinged mucus of bloody show
- A severe headache, vision changes, pain under your ribs, or sudden swelling of the face or hands, which can signal preeclampsia
- Regular, painful contractions that keep building are a sign of labor. Use the contraction timer, see labor and birth, and follow your provider’s when-to-come-in rule
- A fever over 100.4°F (38°C)
Your week 39 checklist
- Keep the hospital bag and the car seat ready, and the route and contacts easy to find
- If you plan to nurse, have a breast pump and a few feeding basics on hand for the first days
- Set out your postpartum recovery comforts so they are ready when you get home
- Keep counting your baby’s movements every day and call the same day for any drop
- Rest, eat well, and let yourself wait, your body is doing quiet work
Appointments and tests around 39 weeks
Weekly visits continue, with movement, blood pressure, and position the main checks.
Your visits stay weekly. Your provider checks your blood pressure, confirms the baby is head down, estimates size, and asks about movements and any early signs of labor. Some providers offer a cervical check to see whether it is starting to soften or open, though this is optional and does not predict the exact day. If your baby’s growth, fluid, or movement needs a closer look, your provider may add a non-stress test or a quick ultrasound. If you go past your due date next week, they will talk with you about monitoring and timing, which we cover on the week 40 page.
A few things worth having on hand now
A note for your partner
The waiting stretch can be hard on both of you. Stay reachable, keep the car ready, and take on the errands and the housework so the person carrying can rest. Small kindnesses land a lot right now, a favorite meal, a foot rub, a calm answer to the tenth is-this-it question. Patience together is the job this week.
Full term, and ready
Reaching full term is genuinely something to feel good about. The last stretch of waiting can test anyone’s patience, but your body and your baby are doing exactly what they should. Whether labor starts tomorrow or a couple of weeks from now, you are right where you need to be.
39 weeks pregnant, common questions
What does full term mean?
Full term runs from 39 weeks 0 days to 40 weeks 6 days. Babies born in this window generally have the most mature lungs and brains and the smoothest starts, which is why providers usually prefer to let labor begin on its own now unless there is a medical reason to act sooner.
Is bloody show a sign labor is close?
It can be. Bloody show is pink or brown-tinged mucus released as the cervix softens and opens, and it often shows up in the days before labor. It does not tell you the exact hour, though. Bright red bleeding is different and is a reason to call your provider.
How will I know when to go to the hospital?
Follow your provider’s specific instructions, often a guide like contractions five minutes apart, lasting a minute, for an hour. Go in sooner if your water breaks, you have bright red bleeding, or your baby’s movements drop. Our labor and birth guide covers the signs in full.
Is it safe to still be pregnant at 39 weeks?
Yes, this is exactly where you want to be. Many babies arrive a few days either side of 40 weeks, and 39 weeks is considered the ideal time. Keep your appointments, keep counting movements, and call your provider with any concern.
Sources
- American College of Obstetricians and Gynecologists (ACOG), definition of full term and late-pregnancy guidance.
- Mayo Clinic, Fetal development: the 3rd trimester.
- MedlinePlus, National Library of Medicine (NIH), Fetal development and prenatal care.
Medical disclaimer: This page is for information and education only and is not a substitute for professional medical advice. Every pregnancy is different. Always follow the guidance of your doctor, midwife, or qualified provider, and contact them with any concerns.