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Third trimester

39 Weeks Pregnant

At 39 weeks pregnant your baby is about the size of a small watermelon. You are in the third trimester, and this week brings its own small changes — for your baby and for you.

Your baby is full term.

Size of
a small watermelon
Length
50.7 cm
Weight
3.29 kg
Trimester
3

Your baby this week

  • The lungs are ready, and the brain and nervous system keep maturing.
  • Antibodies pass from you to your baby, building early immunity.
  • Fat fills out the skin and the wrinkles smooth away.

Your body this week

  • The mucus plug may come away days or hours before labour.
  • Contractions can start at any time now.

Common symptoms

  • A sudden urge to clean, sort and prepare
  • Heavy pressure low in the pelvis
  • Looser stools, which can come before labour

What to expect

The last stretch asks a lot of your body. Sleep gets harder, movement slows down, and your appointments become more frequent. With 1 weeks to go, focus on rest, on knowing the signs of labour, and on having your bag ready.

Tips for this week

  • Know the signs of labour and when to call: regular contractions, waters breaking, bleeding.
  • Plan your route to hospital, and a backup if your driver is unavailable.
  • Take short naps if nights are broken; tiredness builds up quickly now.

Frequently asked questions

How many months is 39 weeks pregnant?

39 weeks is about 9 months. Pregnancy months do not divide evenly into weeks, so counting in weeks is more precise.

How big is my baby at 39 weeks?

At 39 weeks your baby is around a small watermelon — roughly 50.7 cm long and about 3.29 kg. Healthy babies vary a lot around these averages.

What symptoms are normal at 39 weeks pregnant?

The most common ones this week are listed above. Contact your doctor or midwife about heavy bleeding, severe pain, a fever, or any change in your baby’s movements.

Pregnancy weeks are counted from the first day of your last period, so week 1 begins before conception.

This article is for general information only and is not medical advice. Always talk to your doctor or midwife about your own pregnancy.

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