18 weeks pregnant

How is your baby growing at 18 weeks?

Your baby will continue to grown in length, to about 15cm from head to bottom (crown to rump), and will weigh about 200g. The baby's ears are now in their final position and they may start to stand out, away from the side of the head. The brain may be ready to start processing sounds sent to it by the ears. The eyes will continue to fine-tune, with the retinas becoming more sensitive to light and the baby being able to make basic eye movements. The skin is still thin enough to see blood vessels through it. A protective covering of myelin will be developing over the nerves, and your baby may begin to have the sensation of feeling.

Some babies will start getting the hiccups. You won't hear them because fluid fills the windpipe rather than air, but as the baby gets larger in the next few weeks you may be able to feel rhythmic movements inside your bump as the baby hiccups.

Tiny air sacs known as alveoli begin to form in the lungs, and the vocal chords have developed. If air (rather than amniotic fluid) was passing by the chords, you may hear your baby, who will be starting to practise the motions of crying.

If you have an anomaly scan this week, you may be lucky enough to see your baby doing some rolls, twists and kicks, whilst he or she still has plenty of room in the amniotic sac to get in a fair deal of exercise. However, your baby will have both active and sleeping periods, and he or she may be having a nap at the time of the scan.

How are you changing in week 18?

During this stage of pregnancy, your body will be producing more of the fluids and blood cells that help to make up blood, which will increase your blood volume. This can make you feel more thirsty than normal, and you may perspire more often too. Your heart will have to beat harder (not faster) to pump more blood, so it will increase slightly in size. You may also notice that your face is getting a little puffy, which occurs in some women as they retain water due to these circulatory system changes.

You may see tiny red lines on your cheeks or below your eyes, known as spider veins or thread veins. These are tiny blood vessels known as capillaries that become more visible during pregnancy, especially in the first and second trimesters, due to the hormone oestrogen. They can also appear on the neck, chest, hands, forearms and ears. They are harmless and will usually fade away after the birth of your baby.

Meanwhile, your bump and breasts will continue to get larger – people who haven't been told about your pregnancy may by now guess that you are pregnant.