Pregnancy Week 31: Packing Your Hospital Bag and Your Baby's Rapid Growth

8 min read

Quick answer: At 31 weeks your baby measures around 41.1cm crown to heel and weighs about 1.5kg, gaining 200–250 grams a week as fat accumulates. With roughly nine weeks to go, start packing two hospital bags: one for labour and birth, one for after baby arrives. Kicks may feel sharper and smaller. If your baby moves less than usual or their pattern changes, call your midwife or maternity unit immediately.

What parents need to know

At 31 weeks, your baby is gaining weight rapidly and putting the finishing touches on the development of all their major organs. With approximately 9 weeks to go, now is the ideal time to start packing your hospital bag so you're ready if labour comes early. Being prepared early removes a source of stress and allows you to enjoy the final weeks of pregnancy.

Size	Approximately 41.1cm crown to heel
Weight	Around 1.5 kilograms, like a large coconut
Weekly weight gain	Approximately 200–250 grams per week
Weeks to go	Approximately 9 weeks
Hospital bag ready	From around 32–34 weeks

How big is your baby at 31 weeks?

Your baby now measures approximately 41.1cm from crown to heel and weighs around 1.5 kilograms, roughly the weight of a large coconut. They're putting on approximately 200–250 grams per week now as fat continues to accumulate.

What's happening with your baby?

Most of your baby's major organs are now nearly mature. The lungs are continuing to develop and produce surfactant, the substance that allows the air sacs to open and stay open after birth. Your baby's kicks may feel different now — as they grow larger and have less space to move, you may notice fewer large rolling movements and more smaller, sharper kicks and jabs. You should still feel your baby move right up to and during labour. If your baby is moving less than usual, you cannot feel them moving anymore, or there is a change to their usual pattern of movements, call your midwife or maternity unit immediately. Do not wait until the next day. Your baby can now open and close their fists and may even be sucking their thumb.

What to pack in your hospital bag

It's sensible to have your hospital bag ready from around 32–34 weeks, but there's no harm in starting now. You'll need two bags: one for labour and birth, and one for after baby arrives.

For labour: your birth plan; a nightdress or large T-shirt to wear during labour; lip balm (mouth breathing during labour can make lips very dry); massage oil or roller for pain relief; a change of clothes for your birth partner; snacks and drinks for both of you; your maternity notes; phone and charger; headphones and a playlist if you'd like music; and any pain relief items you plan to use such as a TENS machine (these are usually hired in advance).

After birth for you: a loose, comfortable nightgown or pyjamas (front-opening if you plan to breastfeed); dressing gown and slippers; high-absorbency maternity pads (you'll need more than you think); disposable pants or old underwear; toiletries; a going-home outfit in a comfortable size; and any prescribed medication.

For your baby: sleepsuits and bodysuits in newborn and 0–3 months sizes; a hat (hospitals can be warm but newborns lose heat quickly); nappies (newborn size); a car seat (fitted before you leave home); and a blanket or snowsuit appropriate to the season.

Staying hydrated

Staying well hydrated is particularly important in the third trimester. Dehydration can trigger Braxton Hicks contractions and may even cause preterm contractions. Aim for at least 8 glasses of water per day, and more in warm weather or after exercise. If you find plain water boring, try adding a slice of lemon or cucumber for flavour.

When to get help

Some symptoms in pregnancy can be a sign of something serious and need checking quickly. This is who to contact, and how soon.

Call 999 if:

you're bleeding from your vagina and the bleeding is heavy (soaking a period pad soon after putting it on), or you also have severe pain in your tummy, pain in your shoulder, or feel sick, faint, dizzy or lose consciousness
you think your baby is coming now and you have a strong urge to push (ask for an ambulance)
you have severe difficulty breathing (you're gasping, choking or not able to get words out) or your chest feels tight or heavy
you have pain and swelling in one leg and you also feel short of breath or have chest pain. A blood clot in the leg can travel to your lungs, which can be life-threatening
you have possible signs of sepsis, such as breathing very fast, being confused or having slurred speech, blue, pale or blotchy skin, a rash that does not fade when you press it, or a very high or very low temperature. Being pregnant makes sepsis more likely
you do not feel you can keep yourself safe (a mental health emergency is as serious as a physical one)

Always call 999 if you think it's a life-threatening emergency, no matter what stage of pregnancy you are.

Call your midwife or maternity unit now if:

your baby is moving less than usual, you cannot feel your baby moving anymore, or there is a change to your baby's usual pattern of movements
you have light bleeding or spotting, even if you have no pain or only mild tummy pain
you have stomach pain that is severe or does not go away after you've rested for 30 to 60 minutes, or stomach pain with regular cramping or tightenings, lower back pain, or pain when you pee
you're less than 37 weeks pregnant and you have a gush or trickle of fluid from your vagina (this could be your waters breaking), regular contractions or tightenings, period-type pains, or backache that's not usual for you
your waters break, even if labour has not started
you have signs of pre-eclampsia: a severe headache that does not go away with simple painkillers, vision problems (such as blurred vision or seeing flashing lights), pain below the ribs, sudden swelling of the face, hands or feet, feeling very unwell, heartburn that does not go away with heartburn medicines, or being sick (vomiting)
your skin is very itchy (for example, it keeps you awake at night), the palms of your hands or soles of your feet are itchy, or the itching is worse at night. This can be a sign of a liver condition called intrahepatic cholestasis of pregnancy (ICP) that needs urgent treatment
your breathlessness comes on suddenly, you're out of breath when you're lying down, or you're breathless and also have chest pain or feel dizzy
you have pain or swelling in one leg, usually in the calf or thigh. This could be a blood clot (deep vein thrombosis, or DVT), which is more likely when you're pregnant
you have a high temperature (38C or above), or you feel hotter than usual or shivery. A high temperature can be a sign of an infection, so it's important to get it checked
any of your contractions last longer than 2 minutes, or you're having 6 or more contractions every 10 minutes

If your baby's movements change, do not wait until the next day: call immediately, even if it's the middle of the night. Do not use a home doppler to check the heartbeat yourself. Even if you hear a heartbeat, this does not mean your baby is well.

If your waters break, use a period pad (not a tampon) so your midwife can check the colour of the waters, and tell them immediately if the waters are smelly or coloured.

You can also call your midwife or maternity unit if you're unsure or worried about anything.

If you cannot reach them, or you're not sure what to do, call NHS 111.

Speak to your midwife or GP if:

you're worried about your mental health, or stress, anxiety or low mood are affecting your day-to-day life. If you need urgent help for your mental health, call 111 and select the mental health option, or ask for an urgent GP appointment

Go to sleep on your side. From 28 weeks, the safest position to go to sleep is on your side, either left or right. Research suggests that, after 28 weeks, falling asleep on your back can double the risk of stillbirth. This includes daytime naps. If you wake up on your back, just turn onto your side and go back to sleep.

Your week 31 checklist

This week:

Start assembling your hospital bag.
Check you have a suitable going-home car seat.
Stay well hydrated.
Continue monitoring baby's movements.
Enjoy the countdown to meeting your baby.

Sources & further reading

General information, not individual medical advice. Speak to your GP, midwife or health visitor about your baby’s needs.