How many months is 39 weeks pregnant?

39 weeks pregnant puts you in month 9 of pregnancy. Month 9 covers weeks 36 to 40. Providers count in weeks; months are approximate.

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 long and around 3288 g. That is an average; healthy babies vary.

What symptoms should you not ignore at 39 weeks pregnant?

The NHS lists nine signs to treat as an emergency. They are bleeding from the vagina, brown or pink discharge, and severe itching, especially at night. Others are a very bad headache that won't go away, blurry vision or flashing lights, and pain just below the ribs. Watch too for extreme swelling of the feet, ankles, hands or face, stomach pain that won't stop, and a temperature over 37.5°C with no cold or flu. If you have any of them, contact your maternity unit or provider right away. A change in your baby's movements needs a call at once, too.

Is white milky discharge normal at 39 weeks pregnant?

Yes. Lots of thin, white discharge that doesn't smell much is normal now. A slimy blob of yellowish or blood-streaked mucus is likely a show, a sign your cervix is starting to open, though labour may still be days away. Call your midwife or provider about any pink or brown discharge; it's often a show, but they will want to check it isn't other bleeding. Call too if discharge is green, smells bad, itches or stings, or turns watery and keeps leaking, which could be your waters.

Is nausea a sign of labour at 39 weeks?

Not usually on its own. The NHS lists the main signs of labour as contractions, a show, backache, an urge to poo and your waters breaking. Nausea isn't on that list. At 39 weeks, feeling sick is more often indigestion from your baby pressing on your stomach, and small meals and sitting upright after eating can help. Phone your maternity unit without delay if you are vomiting and also have a severe headache, blurred sight, pain under your ribs or swelling that appears quickly, as that mix can point to pre-eclampsia.

What should you be doing at 39 weeks pregnant?

Rest when you can, and stay gently active if you feel like it. Keep your maternity notes, bag and phone within reach. Know when to call: the NHS suggests phoning your hospital or midwife when contractions last at least 60 seconds and come every 5 minutes, or any time you're worried. In the US, check your provider's own rule. If your waters go, call for advice, as your baby is at greater risk of infection once they've gone. And keep noticing your baby's movements every day.

Is constant lower back pain at 39 weeks a sign of labour?

Back pain is common at 39 weeks as your baby moves down and presses on your spine. It can also be a sign of labour, especially when it comes and goes with tightenings or builds in a pattern. Pain that is constant and severe, with no break at all, is different: ACOG advises going to the hospital for constant, severe pain with no relief between contractions. Also call if you have back pain plus a high temperature, bleeding, or pain when peeing. Get emergency help if you lose feeling in your legs, bottom or genitals.

39 Weeks Pregnant

At 39 weeks pregnant, your baby measures about 50.7 cm from head to heel, close to the size of a small watermelon. The skin now has a tougher outer layer that helps with temperature control, and it may still be coated in white, waxy vernix at birth. In US terms, this is the first week of full term. Pregnancy usually lasts around 40 weeks, and most labours start within a week either side of the due date. This page looks at whether it's better to give birth at 39 or 40 weeks, what happens if there are no signs of labour yet, and which types of discharge, pain or nausea need a call.

What trimester is 39 weeks?

Week 39 is in the third trimester, which runs from week 28 until birth. A due date is set at 40 weeks, 1 week from now.

Week 39 — third trimester, month 9; 1 week to go until your due date.
Baby's size — about a mini watermelon, ~50.7 cm.

Not sure it's 39 weeks? Try our due date calculator.

★ Full term — all organs ready.

How big is your baby at 39 weeks?

Size of a

mini watermelon

Length, head to heel

~50.7 cm

Weight

~3288 g

Up from a leek last week to a mini watermelon now.

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. About the size of a mini watermelon.

Is it better to deliver at 39 or 40 weeks?

Both are full term. If your pregnancy is healthy, there's no need to aim for a particular day, and March of Dimes advises letting labour start on its own. The key point is not to plan a birth before 39 weeks without a medical reason. ACOG says babies born at or after 39 weeks have the best chance of healthy outcomes compared with babies born before it.

Some people choose to be induced at 39 weeks. In the ARRIVE trial, 6,106 first-time mothers at low risk in the US were randomly split into two groups: induction at 39 weeks, or waiting for labour. The induction group had fewer caesareans (18.6% vs 22.2%). Serious problems for babies were 4.3% vs 5.4%, a gap too small to be sure it was real. ACOG now says induction at 39 weeks can be discussed if it's your first full-term pregnancy, you're carrying one baby, you're both healthy and your hospital offers it.

In the UK, induction is usually offered if labour hasn't started by 41 weeks. After that, the risk of stillbirth and other problems goes up. Induced labour is usually more painful than labour that starts on its own. It also makes a birth with forceps or a ventouse (suction cup) more likely. The choice is yours, so ask your midwife or doctor to talk through the pros and cons.

Your body at 39 weeks

Strong, possibly regular contractions as labour nears
Pelvic pressure and backache
Loss of mucus plug or bloody show
Nesting energy or exhaustion

No signs of labour at 39 weeks?

That's very common. In England, among labours that started on their own, about 1 in 4 (25.4%) began during week 39, and only about half (50.3%) were under way by the end of it. Week 40 was the single most common week, at 32.5%. A first baby is one of the factors that make a longer pregnancy more likely.

At a checkup after 39 weeks, you may be offered a membrane sweep. Your midwife or doctor sweeps a finger around your cervix to separate the membranes, which releases hormones that may start labour. It can be uncomfortable and cause cramps and some spotting. There's no proven way to start labour at home: hot baths, certain foods, sex and herbal remedies have no good evidence behind them, and herbal products may not be safe. While you wait, keep noticing your baby's movements and call at once if they slow down.

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

39 Weeks Pregnant: your questions

What trimester is 39 weeks?: Week 39 is in the third trimester, which runs from week 28 until birth. A due date is set at 40 weeks, 1 week from now.
How many months is 39 weeks pregnant?: 39 weeks pregnant puts you in month 9 of pregnancy. Month 9 covers weeks 36 to 40. Providers count in weeks; months are approximate.
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 long and around 3288 g. That is an average; healthy babies vary.
What symptoms should you not ignore at 39 weeks pregnant?: The NHS lists nine signs to treat as an emergency. They are bleeding from the vagina, brown or pink discharge, and severe itching, especially at night. Others are a very bad headache that won't go away, blurry vision or flashing lights, and pain just below the ribs. Watch too for extreme swelling of the feet, ankles, hands or face, stomach pain that won't stop, and a temperature over 37.5°C with no cold or flu. If you have any of them, contact your maternity unit or provider right away. A change in your baby's movements needs a call at once, too.
Is white milky discharge normal at 39 weeks pregnant?: Yes. Lots of thin, white discharge that doesn't smell much is normal now. A slimy blob of yellowish or blood-streaked mucus is likely a show, a sign your cervix is starting to open, though labour may still be days away. Call your midwife or provider about any pink or brown discharge; it's often a show, but they will want to check it isn't other bleeding. Call too if discharge is green, smells bad, itches or stings, or turns watery and keeps leaking, which could be your waters.
Is nausea a sign of labour at 39 weeks?: Not usually on its own. The NHS lists the main signs of labour as contractions, a show, backache, an urge to poo and your waters breaking. Nausea isn't on that list. At 39 weeks, feeling sick is more often indigestion from your baby pressing on your stomach, and small meals and sitting upright after eating can help. Phone your maternity unit without delay if you are vomiting and also have a severe headache, blurred sight, pain under your ribs or swelling that appears quickly, as that mix can point to pre-eclampsia.
What should you be doing at 39 weeks pregnant?: Rest when you can, and stay gently active if you feel like it. Keep your maternity notes, bag and phone within reach. Know when to call: the NHS suggests phoning your hospital or midwife when contractions last at least 60 seconds and come every 5 minutes, or any time you're worried. In the US, check your provider's own rule. If your waters go, call for advice, as your baby is at greater risk of infection once they've gone. And keep noticing your baby's movements every day.
Is constant lower back pain at 39 weeks a sign of labour?: Back pain is common at 39 weeks as your baby moves down and presses on your spine. It can also be a sign of labour, especially when it comes and goes with tightenings or builds in a pattern. Pain that is constant and severe, with no break at all, is different: ACOG advises going to the hospital for constant, severe pain with no relief between contractions. Also call if you have back pain plus a high temperature, bleeding, or pain when peeing. Get emergency help if you lose feeling in your legs, bottom or genitals.

Useful at week 39

Pineapple in pregnancy — safe to eat, but no good evidence it starts labour
Exercise in pregnancy — staying gently active while you wait
Pregnancy discharge by trimester — what's normal right before labour
Baby age calculator — track your baby's age in weeks after the birth
Period after pregnancy — when your period may come back after birth

← All weeks: the full pregnancy week-by-week guide

Sources

Checked against the following public guidance on October 2, 2026. Advice can differ between countries; your doctor, nurse or midwife can apply it to you.