39 weeks pregnant: symptoms and baby development
Full term. Everything is ready.
Third trimesterMonth 95 min read
By Solesia, from public clinical guidanceUpdated
Everything that needed building is built. Your baby’s skin has grown a tougher outer layer, the fat is in place, and at 39 weeks they are full term, which is a plain way of saying ready. Their head is very likely settled deep in your pelvis, and that is the pressure you feel low down and the nagging ache at the base of your back. Energy comes in bursts and leaves the same way. Discharge is heavier, and the plug that has sealed the cervix all this time may come away. One week from your due date, the body is quietly getting ready without asking you.
How big is your baby at 39 weeks
About the size of a watermelon
20 in long·7.3 lb
Baby development at 39 weeks
At 39 weeks your baby measures about 20.0 inches from head to heel and weighs around 7.3 pounds, roughly a watermelon. The outer layer of their skin has toughened into the protective barrier it will be after birth, and it looks solid and pink rather than translucent. Vernix still coats it in patches, especially in the creases, and will ease their passage through the birth canal.
The fat that will keep them warm is laid down, mostly in the last month, and their chest and cheeks are rounded. The lungs are ready. The brain, though complete, keeps growing at a pace that will continue through the first years.
They are curled tight with their head down and their chin tucked to their chest, the shape that fits best through the pelvis. Their movements are slow rolls, stretches and pushes now, and you know their busy times and their quiet ones. That rhythm stays the same right up to and into labor.
Your body at 39 weeks
Pressure low in your bump and a dull, nagging backache are expected as your baby settles deeper into your pelvis. Walking is slow, sitting is a project, and turning over in bed takes planning. Lying on your side with a pillow under the bump takes the weight off, and a warm bath at the end of the day eases the back.
Discharge is heavier now, thin and white with little smell, and it is expected. You may notice a jelly-like blob or a few days of stringy mucus, clear, pink or brown-streaked: the plug that sealed the cervix, coming away as the cervix softens. It is a sign of getting ready, not a signal to leave for the hospital. Bright red bleeding is different, and that is a call.
Bursts of energy alternate with days when the sofa is as far as you get, and both are expected. Practice contractions are stronger and more frequent, and some evenings they may seem to be settling into a pattern before fading again. Your body is rehearsing. Sleep is short; nap when you can, eat well, and keep your phone charged.
Common pregnancy symptoms at 39 weeks
- Pelvic pressure. The head deep in the pelvis. Side lying with a pillow under the bump.
- Backache. The baby’s weight low and forward. Warmth, a bath, and a hand on your back when standing.
- Heavier discharge. A softening cervix. Thin and white is expected; a liner, and cotton underwear.
- Losing the mucus plug. The seal on the cervix coming away. Days or weeks before labor; nothing to do.
- Braxton Hicks. Rehearsals, often in the evening. If they build and keep coming, time them.
- Bursts of energy. Hormones getting you ready. Use them lightly, then rest.
- Loose stools. Hormones softening the bowel before labor. Water, and bland food.
When to call your provider at 39 weeks
Itching that is severe, especially at night and on your hands and feet, is worth a same-day call. It is a simple blood test.
Two things are worth a same-day call at any point in pregnancy: bleeding that is more than spotting, and pain that is severe or does not ease. From the second trimester, add fluid leaking and any change in your baby’s usual pattern of movement. You do not need to be sure something is wrong to call; that is what the number is for.
What to do at 39 weeks
- Weekly visit. Blood pressure, urine, bump and heartbeat. Your provider may offer a membrane sweep, a finger sweep around the cervix that can nudge labor along; it is your choice.
- Know when to call. Contractions about a minute long, every five minutes, for an hour; your water breaking, whatever the color; or bright red bleeding. Day or night, that is the call.
- The route and the drive. Who drives, which entrance is open at 2 a.m., where to park, and who has the car seat. Walk through it once so nobody has to think on the day; if it is not done yet, the checklist from 37 weeks still applies.
- The first feed. If you plan to breastfeed, ask for skin-to-skin and the first feed in the first hour. It is on your birth preferences; say it again on the day.
Common questions at 39 weeks
What is a membrane sweep?
During a vaginal exam, your provider runs a finger around the inside of the cervix to separate the membranes from it, which releases hormones that can start labor within a day or two. It is offered from about 39 weeks, it can be uncomfortable, and it works for some women and not others. It is optional.
How long after losing the mucus plug does labor start?
Anywhere from hours to a couple of weeks. Losing the plug means the cervix is softening, not that labor is imminent, and many women lose it in pieces without noticing. It is not a reason to go in; contractions that build, or your water breaking, are.
Is it normal to have diarrhea at 39 weeks?
Yes. The hormones that soften the cervix loosen the bowel too, and loose stools in the last days before labor are common. Drink water, eat plain food, and rest. If it comes with vomiting or a fever, call your provider.
Does full term mean the baby will come this week?
No. Full term means the baby is ready, not that labor is due. About half of first babies arrive after the due date, and 39 to 41 weeks is the ordinary range. Your provider will talk about what happens if you reach 41 weeks without labor starting.
Written from public clinical guidance, including NHS: Week 39, ACOG: How your baby grows, ACOG: Changes in your body, NHS: Signs of labour, NHS: Discharge, NHS: Itching and ACOG: Bleeding. This page is general information, not medical advice, and does not replace your provider.