Your baby

At half way through gestation, your baby is around 16cm from crown to rump and nearly 25cm from head to toe, weighing at 10 ounces – just the size to fit into your cupped hand. But from now on, your baby's growth rate begins to slow down to allow the lungs, digestive and immune systems to mature.

A white, waxy-looking substance called vernix now protects your baby's skin. It is made of sebum (the oil of the skin) and skin cells which drop off your baby’s body. Without vernix, the baby's skin would be deeply wrinkled from its constant exposure to amniotic fluid.

Your baby's muscular and nervous systems are now developed enough so your baby can begin stretching his limbs. If you are carrying a girl, she has six million eggs in her ovaries, her uterus is formed and she's beginning to develop a vagina.

Your progress

Week 20 is a real landmark in your pregnancy – you’re officially half way through! Even more excitingly, you may have an ultrasound scan this week, which you’ve probably been looking forward to for what seems like ages. This is your opportunity to get pictures of your newborn, which you can treasure for years to come.

Hopefully you’re feeling fine at the moment with more energy than you've had for a while. With any luck, all that extra energy and your heightened blood supply may have boosted your libido too (though some women have the opposite experience during pregnancy!)

From now, you’ll gain weight steadily. Most women gain between one to three stone, though more is not unusual. As your uterus pushes your abdomen, your tummy button may flatten or pop out until after the birth. High levels of oestrogen and progesterone are now circulating in your body, which soften and swell your cervix in preparation for childbirth.

What to think about

During your third trimester, it may be useful to take part in some antenatal classes, to prepare yourself and your partner for the experience of labour and birth. So now is a good time to do some research about the antenatal classes available in your area, to ensure you find the right approach for you.

Why are antenatal classes so important? They’re an excellent opportunity for you to get valuable information from a birthing expert who'll help you to realistically understand labour and birth. Plus, you'll be given advice for relaxation during labour so your body can work with a lower level of stress hormones.

At your antenatal classes, you’ll also find out more about your pain relief options and possible methods of medical intervention during labour and birth. It is well worth being fully informed about these in advance, so that you can make informed choices when the time comes.

While giving birth is a healthy, normal event for most women, there are various practical issues you will need to know about, such as your pain relief options and possible methods of medical intervention. It is well worth being fully informed about these in advance at antenatal classes, so you can make informed choices when in labour.

Various kinds of antenatal classes are offered free by the NHS and for a fee by charitable organisations such as the National Childbirth Trust. Courses may involve between three and six sessions of different lengths in the afternoon or evening, or a course might take place over a weekend. You can find out which antenatal classes are available free in your area from your midwife, GP, or health visitor. To find out more about NCT classes, call the National Childbirth Trust (NCT) on: 0870 444 8707