By week 16, your baby is approximately 6 inches and weighs 2 1⁄2 ounces.

Your baby is going to have a growth spurt over the next few weeks! His head is more erect now and her ears and eyes are situated in their final positions. Several of the more complicated body systems are also beginning to function including your child’s urinary and circulatory system. Your baby’s heart pumps around 25 quarts of blood per day.

By now your baby will react if your stomach is poked or pressed. The baby is also becoming sensitive to light outside the womb, but unfortunately that doesn’t mean that it will sleep or rest at the same time you do. Later on in your pregnancy, nighttime movements can make it difficult for mums to get a good night’s sleep. From around 16 weeks onwards, you may be able to feel a flutter in your lower abdomen as the baby moves.

Your uterus is continuing to grow and weighs approximately 8 1⁄2 ounces. Your placenta is also growing, and your body is producing an increased amount of amniotic fluid that helps protect your baby during your pregnancy.

Between 16 and 20 weeks you may be offered amniocentesis. An amniocentesis test uses a sample of the amniotic fluid surround your baby to find out if it has serious genetic conditions such as Down’s syndrome. The test carries a 1 in 100 risk of miscarriage so it is usually only recommended if you’re at high risk of having a baby with these conditions.

From the early stages of pregnancy, your womb presses on your bladder, making you need to urinate more frequently. But if you’re finding it painful to pass urine, there’s blood in your urine, or you feel generally feverish and unwell, you may have cystitis, a urinary infection. It’s particularly common in pregnancy because it’s harder for your bladder to empty fully and your bladder lining becomes softer.
Your body produces 50% more blood when you are pregnant, resulting in more blood circulation through your body. This increase in blood circulation will make your face brighter. Your body is also producing hormones that send your oil glands in to over-drive, leaving your face shiny…. This is what is known as a "pregnancy glow".

You can begin to feel your baby’s first movements between 16 and 20 weeks. If this is your first pregnancy, it may be 20 weeks before you feel your baby move. These first movements are often described as fluttering or gas bubbles.