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

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, but the overall number of movements should stay broadly consistent — report any reduction to your midwife.

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.

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. The overall number of movements should remain broadly consistent, however, and any reduction should still be reported to your midwife. 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.

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.