Fetal development in the 3rd trimester

Pregnancy in the 3rd trimester

This is the third part of a 3 part series on your baby’s development during pregnancy.  If you missed it, you can find out about your baby’s development in the first trimester and second trimester.

What do I need to know?

The late part of your pregnancy is about 3 months long and is also known as the third trimester.  Your baby’s organs can function by 37 weeks and will continue to develop and mature until 40 weeks.  Learn the signs of preterm labour to avoid the problems that preterm babies may experience.

What’s happening and when?


Highlights of Development

27 Taste buds are developed  fetal development 7 months
28 Pupils can react to light
29 Sense of taste is present
30 Baby can hear sounds outside of your body
31 Your immunities are passed to your baby to help fight off infections after birth
32 Babies usually move into a head-down position at this time
33 Lanugo on the body starts to disappear

You may feel your baby hiccup

 fetal development 8 months
34 Skin is smooth, pink, and thickly covered with vernix
35 Baby is putting on fat to help adjust to the cooler temperatures outside of the uterus
36 Baby has established a sleep-wake pattern
37 Your baby is full term but is still maturing  fetal development 9 months
38 There is about 1 litre of amniotic fluid in your uterus
39 The lungs are mature now
40 Your baby is ready to be born


By the end of 40 weeks in pregnancy, your baby is approximately 50 cm long and weighs about 3.2 to 3.6 kg.


Fetal development follows a predictable course but it’s important to note that the measurements mentioned here may vary from your baby’s actual length and weight.  If you have any questions or concerns about your baby’s development, be sure to speak with your health care provider.

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