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Your pregnancy and baby guide

You and your baby at 21 weeks pregnant

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Your baby at 21 weeks

By 21 weeks, your baby weighs around 350g.

From about this stage onwards, your baby will weigh more than the placenta, which, until now, was heavier than your baby. The placenta will keep growing throughout pregnancy, but not as fast as your baby.

Around this time, the baby becomes covered in a very fine, soft hair called lanugo. The purpose of this is not known, but it's thought it may be to keep the baby at the right temperature. The lanugo usually disappears before birth.

You at 21 weeks

Your womb will begin to get bigger more quickly and you'll really begin to look pregnant.

You may feel hungrier than before – try to stick to a balanced, healthy diet in pregnancy, and make sure you know what foods to avoid when you're pregnant.

Things to think about

Stopping smoking in pregnancy completely while you're pregnant is one of the most important things you can do for your baby's wellbeing. Specialist support is available to help you, which will increase your chances of succeeding this time.

Learn about your work rights during pregnancy, including paid time off for antenatal care, and where to get support if you need it.

Explore your birth options if you're pregnant with twins.

The Start4Life site has more about you and your baby at 21 weeks of pregnancy.

You can sign up for Start4Life's weekly emails for expert advice, videos and tips on pregnancy, birth and beyond.

Go back to 20 weeks pregnant

Go to 22 weeks pregnant

See 3 to 42 weeks of pregnancy

Page last reviewed: 04/10/2019
Next review due: 04/10/2022