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31 weeks pregnant

If you’re a first-time mum you will probably have an antenatal appointment this week, so if you have any questions saved up about your final trimester or birth, make a note of them to ask your midwife. Meanwhile, your baby is mostly lazing around laying down fat this week. Alright for some.

By Mumsnet HQ | Last updated Jul 14, 2021

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Your baby at 31 weeks

The skin on your baby’s face is getting smoother now, giving him very squishable cheeks and more of the look of a newborn baby. He also has more fat all over his body, though he’s still fairly scrawny in comparison to how he will look at week 40.

He’s ticking a few other jobs off his to-do list this week, too:

  • Your baby's muscles are coming along nicely and you may see him kicking while you're having a bath – little feet and maybe hands, knees or elbows sticking up under your bump.
  • The adrenal glands, which are small bits of tissue sitting on top of the kidneys, are busy making cortisol. This hormone helps the lungs to make surfactant, essential for breathing as it stops the lungs collapsing after each breath. The adrenal glands in an unborn baby of this age produce 10 times the amount of cortisol an adult’s glands do, showing just how important cortisol is for your baby in aiding lung development.
  • His liver is making bile, which will help him to digest fats, and his pancreas is producing insulin to control his blood sugar.
  • His kidneys are working at full speed to filter the fluid he is swallowing and to make urine. But all this is practice because your placenta is doing everything he needs for now – feeding, breathing and eliminating waste products.
  • If you have a girl, she will be developing her clitoris.

What size is the baby at 31 weeks?

This week, your baby is about 40cm long – about the size of a coconut.

How is your body changing at 31 weeks pregnant?

The extra blood circulating in your body, along with hormonal changes, may already have given you varicose veins. But you may not have been prepared for them to invade your undercarriage…

Vulval varicose veins

Just like ‘normal’ varicose veins (if there is such a thing) these are simply your regular veins, swollen in pregnancy because your uterus presses on the veins higher up in the pelvis creating dilated veins lower down. When they affect your vulval area they feel like a string of grapes.

The following can help with varicosities of all descriptions and locations:

  • Exercise: walk, ride a bike (carefully) or go for a swim.
  • Raise your legs (higher than your heart, ideally). It may look weird but it stops blood pooling in your veins lower down in the body.
  • Don't stand for long periods of time. If you do stand, tighten your calf muscles regularly.

Pregnancy niggles in week 31

If you start to feel as though you’re having contractions around this time, before you pack your hospital bag fear not – they are likely to be Braxton Hicks.

Braxton Hicks contractions

These are tightenings you feel in your uterus as it limbers up for labour. They're said to be painless contractions but – particularly if this isn’t your first pregnancy – can be strong enough to make you stop what you're doing and go “arrghhh”. A terrifying spectacle for passers-by and likely to get you served quicker in the supermarket, but we didn’t tell you that * taps nose *.

Named after the obstetrician who noticed this phenomenon, John Braxton Hicks, in the 19th century, they start at the top of your womb and fan out down your uterus making it feel quite hard.

They tend to last 30-60 seconds or more and will be uncomfortable enough to make you get up, do some breathing exercises or have a warm bath.

They are more common in the evening and may go if you change position. Towards the end of pregnancy you can use them to practise your breathing techniques using a TENS machine.

It is easy to confuse them with real labour pains if this is your first pregnancy. Ask your antenatal team if you’re not sure. If you also have lower back pain, diarrhoea or any other signs of early labour, this may suggest labour is imminent so it’s worth giving your midwife a ring.

Leaky boobs

Your body is preparing for birth and breastfeeding, which means you may experience some leakage of 'pre-milk', or colostrum, in the weeks running up to the big arrival. You can put nursing pads in your bra to absorb some of the fluid.


The strain of carrying around your baby may be taking its toll on your back by 31 weeks. Prenatal yoga classes can help relieve the pain, as can doing some gentle stretches at home.

Can I fly at 31 weeks pregnant?

  • Airlines vary in their willingness to take you, but the Royal College of Obstetricians and Gynaecologists says it is safe to fly before 37 weeks if you are only carrying one baby.
  • There may also be medical reasons why you should avoid a plane trip, such as if you're anaemic or have had a previous premature birth, so be sure to check with your doctor if you have any concerns.
  • There's no evidence that the change in air pressure or humidity will harm you or your baby. You might be quite uncomfortable flying if you've got a big bump, though (an excuse to travel first class, surely?).
  • If you are more than 28 weeks, most airlines will ask for a letter from your doctor saying it's safe for you to travel.
  • You may find your legs swell more and the lower air pressure can increase the likelihood of you getting a nose bleed (since your nose is already congested in pregnancy). Try to factor in some decent rest time once you arrive at your destination (hello, mid afternoon nap) and elevate your legs to allow the swelling to go down.
  • There is a risk, especially with flights over four hours long, of developing a blood clot in your leg so you should discuss this with your midwife.

Things to think about during week 31 of pregnancy

It can feel as though you’re expected to be permanently excited and full of the joys of impending motherhood while you’re pregnant, but for most women it’s not like that.

Normal life with all its irritations continues around you and, let’s be honest, there’s plenty to worry about – from finances, to the health of you and your baby, to how friendships and relationships may change. And that’s before helpful folk get started with the birth horror stories…

Birth anxiety

There may be some superhuman pregnant women who don't feel anxious when they remember their baby has to come out somehow (and it’s probably not going to take an Uber), but most women do get worried. You may not only be anxious about giving birth but also that your baby will be ok.

Talking to other women can be very helpful, but understand some women like to tell horror stories about giving birth, so divide the horror in their stories by at least half, and read some positive birth stories, too, for balance.

The odds of having a healthy baby are overwhelmingly in most women's favour, but we all know that's not guaranteed, which is why we all feel a little anxious. This anxiety for your baby will last for the rest of their life – even when your baby is married with his or her own baby.

If you're feeling low you might find it helps to discuss this with other mums who've been in a similar position – you can post on our pregnancy Talk forum or our mental health forum any time, anywhere. Whatever you do, don't suffer in silence – if you're finding the going extra tough, talk to your GP or midwife.

Choosing a birthing partner

If you haven't already, you'll want to decide on a birthing partner in preparation for labour. A birth partner is someone you know and trust who will remain by your side throughout your labour. They will support you when the going gets tough (because let's face it, this birthing business ain't no walk in the park) and can be anyone you choose – such as the father of your child, your mum, a good friend or a doula.

You can pop your birth partner information on your birth plan. It's also worth thinking about a back-up birth partner for the unlikely scenario of your chosen partner being unavailable on the day (we're talking for emergency reasons, here).

What to buy

If you haven’t already, now could be the time to make some of those big purchases for your baby, such as a travel system, car seat and highchair. You won’t feel like traipsing round the shops for much longer and you may want to try a few of these out in person before buying.

To narrow down the field, have a look at the reviews on Mumsnet first – and check our list of newborn essentials, to make sure nothing gets forgotten.

What's next: 32 weeks pregnant