How many months is 31 weeks pregnant?

31 weeks pregnant puts you in month 7 of pregnancy. Week 31 is the last week of that month, and month 8 starts at week 32. Providers count in weeks; months are approximate.

How big is the baby at 31 weeks?

At 31 weeks, the baby is about the size of a coconut, roughly 41.1 cm long and around 1502 g. That is an average; healthy babies vary.

Is it safe to deliver at 31 weeks?

A baby born at 31 weeks has a very good chance of survival, but it is still premature. English data from 2008 to 2014 show that 98.1% of babies born at 31 weeks and admitted to a neonatal unit left hospital alive. Their lungs may not be fully mature. So they need a stay in a neonatal unit, and some face health or development problems. If an early birth is likely, doctors usually give steroid shots to help the baby's lungs. Before 32 weeks, they may also give magnesium sulphate, which may lower the risk of cerebral palsy.

What symptoms should you not ignore at 31 weeks pregnant?

Get help straight away for bleeding, fluid leaking, painful or regular tightenings, or if your baby's usual movements change. Also watch for signs of pre-eclampsia, which is most likely from 20 weeks on. These include a bad headache that painkillers don't fix, and blurred sight or flashing lights. Others are pain under your ribs, heartburn that antacids don't help, and vomiting. Your face, hands or feet may also puff up suddenly. Call your maternity unit or provider rather than waiting for your next checkup.

Are period-like cramps normal at 31 weeks pregnant?

Mild tightenings that come and go are usually Braxton Hicks. They stay irregular and don't get stronger. They often ease if you walk, change position, drink water or empty your bladder. Period-like cramps that keep coming back are different. With or without diarrhoea, they may mean labour is starting early. That's more likely if they come with a low, dull backache, a feeling of pressure low down, or discharge that turns watery or bloody. If you're not yet 37 weeks, phone your provider or maternity unit about them straight away.

How many days are left at 31 weeks pregnant?

If your due date is at 40 weeks, you have 9 weeks, or 63 days, to go. It's very unlikely you'll go beyond another 9 or 10 weeks. You could also meet your baby sooner. From 37 weeks, just 6 weeks from now, a baby is no longer counted as premature, and US doctors see 39 weeks as full term. Your due date is only a best guess, so use our due date calculator to find the exact date.

What should I know at 31 weeks pregnant with twins?

Your babies' birth may be only weeks away. Most twins are born early, and the NHS offers a planned birth date, because carrying on past it can be risky. It is usually 37 weeks if the twins have separate placentas, 36 weeks for identical twins sharing one, and 32 to 33 weeks for the rare twins who share both a placenta and a sac. The chance of labour starts to rise from about 32 weeks with twins, so airlines may not let you fly. Make sure you know the signs of early labour.

31 Weeks Pregnant

At 31 weeks pregnant, your baby is about 41.1 cm head to heel and close to the size and weight of a coconut. It's very active, sucking its fingers and doing the odd somersault, and it looks plumper and less wrinkled each day. Because the baby now passes urine, the amount of amniotic fluid keeps going up. It may also start to recognise voices from outside the womb. Many people feel practice contractions around now. This page covers the 31-week checkup and low placenta rechecks, your bump, whether it's safe to give birth at 31 weeks, cramps, and symptoms you should never ignore.

What trimester is 31 weeks?

Week 31 is in the third trimester, which runs from week 28 until birth. A due date is set at 40 weeks, 9 weeks from now.

Week 31 — third trimester, month 7; 9 weeks to go until your due date.
Baby's size — about a coconut, ~41.1 cm.

Not sure it's 31 weeks? Try our due date calculator.

How big is your baby at 31 weeks?

Size of a

coconut

Length, head to heel

~41.1 cm

Weight

~1502 g

Up from a cabbage last week to a coconut now.

Baby development at week 31

The brain is developing rapidly. The fetus can turn its head from side to side and is making breathing movements, though the lungs aren't finished. Most major organs are well formed, while the lungs and brain are still maturing. Most of the remaining work is putting on weight. About the size of a coconut.

What an ultrasound shows at 31 weeks

A scan isn't routine at 31 weeks. In the UK, first-time parents are offered a checkup this week instead, and in the US you're likely seeing your provider every two weeks by now. The checkup includes a bump measurement, blood pressure and urine checks, and questions about the baby's movements. Your midwife or doctor will also press gently on your belly to find out whether the baby is head-down or not. It's a good time to talk about your birth preferences and how you'll know labour has started.

A scan is likely soon if your placenta was lying low at your anatomy scan. The recheck is usually at about 32 weeks. In 9 out of 10 pregnancies, the placenta has moved up out of the way by then, as the womb grows. If it is still low or covering the cervix, a caesarean birth is usually advised. Until your recheck, call straight away if you have painless, bright red bleeding from the vagina.

Your body at 31 weeks

Leaking colostrum (early breast milk) for some
Backache
Frequent urination as the baby presses on the bladder
Braxton Hicks contractions

Your belly at 31 weeks

At 31 weeks, your fundal height is typically close to 31 cm, within about 2 cm either way. Your baby and bump are still growing, and in a couple of weeks you'll both go through a final growth spurt. Much of the baby's remaining growth is fat.

Now and then, you may feel your bump hardening for 20 to 30 seconds before it softens again. These are Braxton Hicks contractions, and they shouldn't hurt. Some people also feel the baby settle lower and see the bump drop a little. Other babies stay high and don't move down into the pelvis until labour starts. Both are normal.

Tips for week 31

Breast pads can help if colostrum leaks
Support your lower back when sitting and standing
Consider finalising your birth plan

31 Weeks Pregnant: your questions

What trimester is 31 weeks?: Week 31 is in the third trimester, which runs from week 28 until birth. A due date is set at 40 weeks, 9 weeks from now.
How many months is 31 weeks pregnant?: 31 weeks pregnant puts you in month 7 of pregnancy. Week 31 is the last week of that month, and month 8 starts at week 32. Providers count in weeks; months are approximate.
How big is the baby at 31 weeks?: At 31 weeks, the baby is about the size of a coconut, roughly 41.1 cm long and around 1502 g. That is an average; healthy babies vary.
Is it safe to deliver at 31 weeks?: A baby born at 31 weeks has a very good chance of survival, but it is still premature. English data from 2008 to 2014 show that 98.1% of babies born at 31 weeks and admitted to a neonatal unit left hospital alive. Their lungs may not be fully mature. So they need a stay in a neonatal unit, and some face health or development problems. If an early birth is likely, doctors usually give steroid shots to help the baby's lungs. Before 32 weeks, they may also give magnesium sulphate, which may lower the risk of cerebral palsy.
What symptoms should you not ignore at 31 weeks pregnant?: Get help straight away for bleeding, fluid leaking, painful or regular tightenings, or if your baby's usual movements change. Also watch for signs of pre-eclampsia, which is most likely from 20 weeks on. These include a bad headache that painkillers don't fix, and blurred sight or flashing lights. Others are pain under your ribs, heartburn that antacids don't help, and vomiting. Your face, hands or feet may also puff up suddenly. Call your maternity unit or provider rather than waiting for your next checkup.
Are period-like cramps normal at 31 weeks pregnant?: Mild tightenings that come and go are usually Braxton Hicks. They stay irregular and don't get stronger. They often ease if you walk, change position, drink water or empty your bladder. Period-like cramps that keep coming back are different. With or without diarrhoea, they may mean labour is starting early. That's more likely if they come with a low, dull backache, a feeling of pressure low down, or discharge that turns watery or bloody. If you're not yet 37 weeks, phone your provider or maternity unit about them straight away.
How many days are left at 31 weeks pregnant?: If your due date is at 40 weeks, you have 9 weeks, or 63 days, to go. It's very unlikely you'll go beyond another 9 or 10 weeks. You could also meet your baby sooner. From 37 weeks, just 6 weeks from now, a baby is no longer counted as premature, and US doctors see 39 weeks as full term. Your due date is only a best guess, so use our due date calculator to find the exact date.
What should I know at 31 weeks pregnant with twins?: Your babies' birth may be only weeks away. Most twins are born early, and the NHS offers a planned birth date, because carrying on past it can be risky. It is usually 37 weeks if the twins have separate placentas, 36 weeks for identical twins sharing one, and 32 to 33 weeks for the rare twins who share both a placenta and a sac. The chance of labour starts to rise from about 32 weeks with twins, so airlines may not let you fly. Make sure you know the signs of early labour.

Useful at week 31

Pregnancy due date calculator — count down the exact days to your due date
Fetal viability — what changes with each week a baby stays in the womb
Pregnancy discharge by trimester — how to tell normal discharge from leaking fluid
Flying while pregnant — airline cut-offs as the third trimester goes on
Pregnancy weeks to months — 31 weeks is the last week of month 7

← 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.