Week 13
Your baby weighs around 25g1.
Your baby's ovaries or testes are fully developed inside their body, and the genitals are forming outside their body.
Where there was a swelling between the legs, there will now be a penis or clitoris growing, although you won't usually be able to find out the sex of your baby at an ultrasound scan at this stage.
Week 14
At 14 weeks, the baby is about 85mm long from head to bottom.
Around now, the baby begins to swallow little bits of amniotic fluid, which pass into the stomach. The kidneys start to work and the swallowed fluid passes back into the amniotic fluid as urine.
Week 15
Around this time, your baby will start to hear – she or he may hear muted sounds from the outside world and any noises your digestive system makes, as well as the sound of your voice and heart.
The eyes also start to become sensitive to light. Even though your baby's eyes are closed, they may register a bright light outside your tummy.
Week 16
The muscles of the baby's face can now move and the beginnings of facial expressions appear. Your baby can't control these yet.
The nervous system continues to develop, allowing the muscles in your baby's limbs to flex. Around this time, your baby's hands can reach each other – they can form a fist, and hold each other when they touch.
Your body at 4 months pregnant
If you've been feeling sick and tired with morning sickness, you'll probably start to feel better when you're around 13 or 14 weeks pregnant.
Some women start to experience an increased sex drive around this time, possibly as a result of pregnancy hormones or increased blood flow to the pelvic area. Some women don't, and this is perfectly normal.
You'll notice a small bump developing as your womb grows and moves upwards. If you've been feeling the urge to pass urine more often over the last few months, it's because your womb was pressing on your bladder. This should ease off now.
See your doctor if you notice any pain when you urinate. Urinary infections can happen in pregnancy, and it's important to treat them quickly to reduce the risk of kidney infections.
Tips for 4 months pregnant
Headaches
Getting headaches during pregnancy is common, but if they're severe, they could be a sign of something serious.
Teeth and gums
Your teeth and gums need a little extra care in pregnancy.
Find out who's looking after you
Get to know who's who in the maternity team and learn more about each of their roles during your pregnancy.
