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Pregnancy Week by Week - 37 to 40 weeks

27 Nov, 2023

A weekly breakdown from 37 to 40 weeks

Week 37

Your baby is the size of a jackfruit. The coordination of sucking and swallowing has matured for feeding and nourishment after birth. Your baby has developed more dexterity with the ability to grasp smaller objects like the toes or nose. For first pregnancies, this week your baby may start to engage or move down into the pelvis in preparation for birth. For subsequent pregnancies, this engagement process may not occur until labour has commenced.

Week 38

Now the size of a leek, your baby's brain continues to mature. The cerebral cortex has experienced significant growth which is responsible for functions such as movement, thinking and perception. The lungs manufacture surfactant to assist baby when taking its first breath. As the body prepares for birth, common symptoms experienced include pelvic pressure, cramping, backache or diarrhoea.

Week 39

Your baby is the size of a pumpkin. Most of the organs are mature and fully functioning. Baby’s brain and lungs can function effectively outside the womb, although they continue to mature during childhood. Baby boy testicles are fully descended into the scrotum. Your baby may descend lower into the pelvis reducing upper abdominal pressure, with many pregnant parents reporting the ability to breathe more easily. Braxton Hicks contractions are common, described as irregular tightenings of the uterus preparing the body for birth.

Week 40

You baby is the length of a watermelon. The bones in baby’s skull remain soft for birth as they overlap as your baby descends the birth canal. Although you have reached this milestone, only approximately 5% of babies are born on their expected due date. It is unknown what causes the onset of labour although believed to be a combination of physical, hormonal and emotional factors occurring between the pregnant parent and baby.

Disclaimer: The fruits and vegetables used each week is a guide only and aims to compare baby's approximate length and weight. Each pregnancy and baby are unique.

Written by PBC Expo Midwife Hayley Hall

Midwife, Birth Educator and Mum of 4

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