Quick answer: At 34 weeks your baby measures around 45cm and weighs about 2.1kg, and most babies have turned head-down ready for birth. The NHS recommends the whooping cough vaccination between 16 and 32 weeks, ideally around 20 weeks, but you can still have it up to labour if you missed it. If your baby is breech, your midwife will discuss options such as ECV at 36 to 37 weeks.
What parents need to know
You're at 34 weeks — with just six weeks to go, the end is in sight! This week brings an important antenatal appointment at which you'll be offered the whooping cough vaccination. Your baby is also beginning to settle into a head-down position in preparation for birth. Let's look at what's happening this week.
| Length | Around 45cm crown to heel |
|---|---|
| Weight | Around 2.1kg, like a small watermelon |
| Weeks to go | Six weeks until your due date |
| Whooping cough vaccine | Offered 16–32 weeks, ideally around 20 weeks |
| ECV timing | Usually offered between 36 and 37 weeks |
How big is your baby at 34 weeks?
Your baby now measures approximately 45cm from crown to heel and weighs around 2.1 kilograms — roughly the weight of a small watermelon. Their skin is becoming smoother and pinker as fat continues to be laid down beneath the surface.
What's happening with your baby?
The majority of babies have turned head-down by 34 weeks, though there is still time for those who haven't. At your 34-week appointment, your midwife will check your baby's position by feeling your bump (a technique called palpation). Your baby's fingernails are now fully grown and some babies scratch themselves in the womb, which is why some newborns arrive with tiny scratches on their faces. The vernix caseosa (the white waxy coating on your baby's skin) is thickening as birth approaches.
The whooping cough vaccination
The NHS recommends that all pregnant women receive the whooping cough (pertussis) vaccination between 16 and 32 weeks of pregnancy, with the ideal time being around 20 weeks. However, if you missed it, you can still have it up to the point you go into labour. The vaccine works by triggering your immune system to produce antibodies, which are then passed to your baby through the placenta before birth. These antibodies protect your baby in the crucial first weeks of life before they are old enough to be vaccinated themselves at 8 weeks. Whooping cough can be extremely serious and even fatal in very young babies. The vaccine is safe in pregnancy and does not contain live bacteria, so it cannot cause infection.
Birth presentation and breech babies
At 34 weeks, if your baby is still in a breech position (bottom or feet down), your midwife will discuss options with you. Most units offer a procedure called External Cephalic Version (ECV) between 36 and 37 weeks, where a doctor attempts to turn the baby by applying pressure to the outside of your abdomen. ECV has a success rate of around 50% and carries a small risk of complications, so it's done in a hospital setting. If ECV is unsuccessful or you prefer not to have it, your care team will discuss the options for a planned caesarean or, in some units, a planned vaginal breech birth.
What's happening in your body?
You may notice that your bump has dropped lower, a sign that your baby is moving down into the pelvis in preparation for birth. This is known as 'engagement' or 'lightening'. For first-time mothers, engagement often occurs in the last few weeks of pregnancy; for subsequent pregnancies, the baby may not engage until labour begins. When the baby drops, you may find it easier to breathe but experience increased pressure on your bladder.
Your week 34 checklist
This week:
- Attend your 34-week midwife appointment.
- Receive your whooping cough vaccination if you haven't already.
- Ask about your baby's position.
- Finalise your birth plan.
- Ensure your hospital bag is complete.
Frequently asked questions
Can I still have the whooping cough vaccine at 34 weeks?
Yes. The NHS recommends it between 16 and 32 weeks, ideally around 20 weeks, but if you missed it you can still have it up to the point you go into labour.
Is the whooping cough vaccine safe in pregnancy?
The vaccine is safe in pregnancy and does not contain live bacteria, so it cannot cause infection. It triggers antibodies that pass to your baby through the placenta, protecting them before their own vaccinations at 8 weeks.
What happens if my baby is breech at 34 weeks?
Your midwife will discuss options. Most units offer External Cephalic Version between 36 and 37 weeks, with around a 50% success rate. If it is unsuccessful or declined, your team will discuss a planned caesarean or vaginal breech birth.
What does it mean when your bump drops?
It means your baby is moving down into the pelvis ready for birth, known as engagement or lightening. You may find breathing easier but feel increased pressure on your bladder.
Sources & further reading
- NHS — You and Your Baby at 34 Weeks Pregnant
- NHS — Whooping Cough Vaccination in Pregnancy
- RCOG — External Cephalic Version (ECV) and Breech Baby
- Tommy's — Week 34 of Pregnancy
General information, not individual medical advice. Speak to your GP, midwife or health visitor about your baby’s needs.
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