21 weeks pregnant

How is your baby growing at 21 weeks?

As the legs are straighter, your baby will now be measured from head to heel (not head to bottom). Your baby should be about 27cm long and weigh about 360g. Up until now the placenta has weighed more than the baby, but that's about to change, as the baby will be steadily gain weight at a faster pace, with fat accumulating on the body. If the size of the baby's head is measured during a scan, the operator may be able to estimate the week in which the baby will be born. Your baby may now be able to recognise the sound of your voice.

Eyebrows, eyelashes and fingernails should all be formed, and your baby may even scratch him or herself. As the taste buds mature, your baby's sense of taste will be developing, and soon your baby may even be able to detect tastes in the amniotic fluid while taking in gulps of the liquid as he or she practises swallowing.

Your baby's bones should be ready to start making red blood cells – these were previously produced in the baby's liver and spleen. The baby's intestines may also be ready to absorb small amounts of sugar found in the amniotic fluids, marking the first time the placenta is not providing all of the baby's nourishment.

Now that you can probably feel your baby moving, don't expect to feel the movements all the time. Sometimes the baby is sleeping – hopefully this won't be the case when you have a scan, so you can enjoy seeing your baby being active.

How are you changing in week 21?

Most women enjoy this period of pregnancy, when the symptoms of the first trimester, such as morning sickness, disappear but before they get so large that they feel uncomfortable. However, there is likely to still be some discomfort.

Leg cramps in the calf muscles are common, occurring in about a third of pregnancies, but experts are not sure why. They can start at about 20 weeks and occur more frequently in the third trimester. They may be caused by changes to your blood circulation or because your muscles are tired from carrying extra weight, for example. The cramps often occur at night, causing a sharp pain that can last for up to 10 minutes.

What you need to know in week 21

If you have a leg cramp, stretch your muscles by straightening your leg, pushing down at the heel and then rotating your ankles and feet. Your muscle may feel a bit tender afterwards but the pain will ease.

Now is a good time for both you and your partner to talk to your baby on a regular basis. Choose a quiet place without other background noises and speak in a calm regular tone. Your baby will get to recognise your voices. You can simply read to your baby, tell him or her a story, or sing a soft song. Your baby may also enjoy quiet music with simple melodies – research has shown that unborn babies are more restful when this type of music is played, especially when compared to loud music that can make a baby jump.

Next: 22 weeks pregnant

Additional pregnancy week by week pages:
23 weeks pregnant | 24 weeks pregnant
25 weeks pregnant | 26 weeks pregnant