By week 13, you're at the start of your second trimester and your baby weighs around 25g and is around 85mm long from head to bottom. It's at this stage that your baby will start to swallow bits of amniotic fluid (your waters) which pass into his or her stomach. Your baby's kidneys will start to work and they will pass the swallowed water back into the amniotic fluid as urine.
By week 15 your baby will start to hear muted sounds from the outside world, noises from your digestive system, your heartbeat and your voice. It's around this time that you might like to think about playing some music, singing or talking to your bump.
You baby's eyes will start to become sensitive to light, even though your baby's eyes are closed they may start to register changing light outside your tummy.
By week 16 the muscles in your baby's face begin to move and the beginnings of facial expressions appear, although your baby won't be able to control these just yet.
Baby's nervous system will continue to develop allowing baby's muscles to flex in each of his or her limbs. It's also around this time that your little one's hands can reach each other, and can even form a fist.
There's good news if you've been feeling sick and tired with morning sickness as it's usually around weeks 13 and 14 that you'll probably start to feel a bit better.
It's also an exciting time as you'll start to notice a small bump appearing.
Make sure you're eating well and getting plenty of rest. Try to incorporate some exercise into your daily routine and think about small changes you can make towards a healthier lifestyle that you can then maintain throughout your pregnancy.
You'll also need to start thinking about informing your employer of your pregnancy so that you can arrange maternity leave and pay if you're entitled to it.
For more information on pregnancy health and advice go to www.nhs.uk/Start4Life