Congratulations! By the end of week 12 you'll have completed your first trimester. You're now one third of the way there, and the hardest part of pregnancy is behind you (of course, that's not including labor!). If you haven't yet had your first ultrasound, you should be having this sometime within the next week or two.

As the first trimester comes to an end, you're hopefully starting to feel much more like your old self. Human chorionic gonadotropin (HCG) levels have peaked now, that's the hormone that's partly responsible for the morning sickness and tenderness, so you should find you're feeling much better. If you're not, speak to your Doctor or Midwife, as it's important you're eating well and keeping hydrated at this time.

Baby: What's Happening?

Your baby is now at least half a centimetre long, or around 2 to 2.5 inches. He or she weighs in at around half an ounce and is getting bigger and heavier by the day. The brain and central nervous system are becoming more complex now, and are allowing your baby to make more deliberate movements inside your womb.

Your baby's reflexes are improving around now, and he or she can move it's tiny fingers and toes. Your baby may be sucking its thumb and can even respond to your touch, although you're unlikely to feel any movement yet, especially if this is your first pregnancy. It may seem strange that this little lime-sized person can do so much already, but babies are much more clever than we often give them credit for!

Your baby's eyes have settled in their final position on the face now, and the belly is becoming more rounded (much like yours is!). The bone marrow is producing infection-fighting white blood cells and the digestive system is starting to work, although it won't really be doing much until after the birth when your baby starts taking in breastmilk or formula.

You: What's Happening?

The good news is that your hormones start to settle down around now, so all those early pregnancy symptoms should start to reduce. It may still take a week or two for them to disappear completely, so don't expect it to happen overnight!

The big change for you this week is the size of your uterus. It's so big now that the top has started to protrude over the top of your pelvic bone, and if you see a Midwife around this time they'll probably be able to feel it. You may not be able to feel it yourself yet, but you'll certainly know it's there! At appointments, your Midwife will measure your uterus from your public bone to the highest point that the uterus can be felt. This gives a good indication of how your baby is growing.

Because your lower abdomen doesn't have the same bone support as the pubic region, your uterus will now start to show through. It may only be small, but you should start to notice a bit of rounding out. You may find bending forwards is more challenging, although this will be nothing compared to during the third trimester!

Handy Hints

You may decide you'd like to go public with your pregnancy around now. There's two reasons that the 12 week mark is a good time to share your happy news; firstly, you'll start to become noticeably pregnant and won't be able to hide the fact for much longer anyway, and, secondly, the chance of anything going wrong reduces significantly at this time.

Around three quarters of all miscarriages happen within the first twelve weeks, and if you see a healthy heart beating away at your first scan, that's a good sign that your baby is just fine. Announcing your pregnancy to friends and family may be nerve wracking, but it's also one of the most exciting times!

If you're making your news known at work, you may wish to ask to see a copy of your company's maternity policy, which should include details on risk assessments, maternal care and maternity leave. However, if you're not ready for your colleagues to know yet, they don't have to. Depending on your country of residence, you don't need to officially inform your employer until between 25 and 35 weeks of pregnancy. Make sure you know what your country's requirements are in advance.