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Pregnancy health centre

40 weeks pregnant

WebMD Medical Reference
Medically Reviewed by Dr Rob Hicks


How is your baby growing at 40 weeks?

On average, a baby born in week 40 may be 51cm long and weigh about 3.5kg (7.5lb), and about 15% of his or her body is fat. Most of the vernix will have disappeared, and if your baby is born even later than 40 weeks – and this often happens – his or her fingernails may be long enough to scratch.

In preparation for birth your baby should be in the foetal position – head down, legs tucked into his or her chest and knees against nose. The bones in your baby's head will be able to overlap each other to make it possible for the baby to exit through your vaginal canal.

How are you changing in week 40?

If you are still waiting for the first signs of labour (see week 39), more than likely you are feeling a bit impatient, and you might be a bit emotional too. If you are wondering if your baby will ever be born, remember that only about 5% are born on their actual due date, with childbirth often occurring up to 2 weeks early or 2 weeks late – first-time mums often have late babies. If you aren't showing signs of labour by the beginning of week 42, you may be offered induction to encourage your baby to greet the outside world.

The first stage of labour may seem to have taken ages to arrive, but the second and third stages will seem to speed by. The second stage of pushing the baby through the vaginal canal typically lasts for about an hour if it is the birth of a first baby or after just a few pushes in second and subsequent births. However, the second stage could last more than 2 hours, and if there are signs of stress in your baby, intervention with forceps, a vacuum extraction or caesarean may be considered. The third and last stage of labour is delivering the placenta, which often takes a few minutes. You will be given an injection to speed up the delivery of the placenta – it will be checked to ensure none of the placenta remains inside you, which could lead to infection.

What you need to know in week 40

If this is your first pregnancy, you will have an antenatal appointment at week 40, in which your midwife or doctor will measure the size of your womb, measure your blood pressure and test your urine for protein.

If your pregnancy goes into week 41 or beyond, whether it is your first baby or not, you will have an antenatal appointment each week so that your midwife or doctor can measure the size of your womb, measure your blood pressure and test your urine for protein.

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