39 weeks pregnant: baby's development and preparing for after the birth

Your baby is now the size of mini watermelon - and you’re probably feeling a bit like a whale. Hang on in there - you’ll soon be meeting your baby.

Your baby’s development this week

Your baby’s immune system can now protect them against a variety of infections. This is mainly because you have transferred yours to them through your blood.

Babies can continue getting antibodies from you through breastfeeding after birth, if this is what you are hoping to do.

Your pregnancy symptoms in week 39

Feeling uncomfortable

The third trimester of pregnancy can be physically and emotionally challenging. You may be feeling quite tired and uncomfortable.

“I remember at this point getting off the sofa felt like a marathon event. I personally found that discomfort and not knowing when it would end difficult to deal with mentally.”

It’s important to try and relax and keep stress to a minimum. See our 10 tips to relax in pregnancy.

A ‘show’

When you are pregnant, a small plug of mucus blocks the entrance to your cervix (the neck of your womb).

This sticky, jelly-like often pink mucus is called a show. It may come away in 1 blob or in several pieces. It may be pink because it contains a small amount of blood. This means the cervix is opening. Labour may start quickly or take a few days.

Not everyone has a show.

If you're losing any fresh blood (like a period), it may be a sign something is wrong, so phone your hospital or midwife straight away.

Braxton Hicks contractions

Braxton Hicks contractions can be quite powerful towards the end of your pregnancy and it’s easy to mistake them for labour contractions.

Braxton Hicks may be uncomfortable but not painful. When you have a contraction, your womb tightens and then relaxes. For some people, contractions may feel like extreme period pains. Contact your midwife or maternity unit if you think you are having contractions.

What to do in week 39

Being healthy in the last weeks of pregnancy

Carry on eating a healthy diet. You may need around 200 extra calories a day during the last part of your pregnancy. You also might feel more comfortable if you eat little and often.

Keep up with your pelvic floor exercises too. Toning up your pelvic floor muscles will benefit you during labour and birth, as well as after your baby is born.

Sleeping safely for your baby

When you reach your third trimester, the advice is to go to sleep on your side because research has shown that going to sleep on your back is linked to an increased risk of stillbirth. This advice includes daytime napping and night sleeping. Read more about safe sleep positions in pregnancy.

Can anything really help start labour?

There are some things you can do to try and start labour naturally. But be aware that there is not enough scientific evidence to prove that any of them work. It’s very important to get advice from your midwife before trying anything to get your labour going.

“I was very stressed and impatient at the end as I was overdue. I did not find anything that worked. As difficult as it is, relaxing is the best thing to do at this stage.” 

After your baby is born

The first 12 weeks after your baby is born can be both exciting and overwhelming. We have lots of information to help you find your feet as a new parent.

1. Regan, Lesley (2019) Your pregnancy week by week, Penguin Random House, London

2. NHS. Signs that labour has begun. https://www.nhs.uk/pregnancy/labour-and-birth/signs-of-labour/signs-that-labour-has-begun (Page last reviewed: 30 November 2020 Next review due: 30 November 2023)

3, NICE (2010) Weight management before, during and after pregnancy. NICE guideline 124. National Institute for Health and Care Excellence. https://www.nice.org.uk/guidance/ph27

4. Heazell AEP, Li M, Budd J, Thompson JMD, Stacey T, Cronin RS, Martin B, Roberts D, Mitchell EA, McCowan LME. Association between maternal sleep practices and late stillbirth – findings from a stillbirth case-control study. BJOG2017; https://doi.org/10.1111/1471-0528.14967.

Review dates
Reviewed: 11 July 2022
Next review: 11 July 2025