16 Weeks

You are now 16 weeks pregnant (or in your 17th week if that's how you prefer to count it).

Your baby is now about the size of an avocado, is about 10.1cm long from crown to rump, and weighs approximately 100g. In the next three weeks she'll go through a tremendous growth spurt, doubling her weight and adding inches to her length.

In or out of the uterus (womb), babies are playful creatures. Yours may already have discovered her first toy – the umbilical cord – which she'll enjoy pulling and grabbing. Sometimes she may even clutch it so tight that less oxygen gets through, but don't worry – she doesn't hold onto it long enough to harm himself.

The circulatory system and urinary tract are in full working order, and she's inhaling and exhaling amniotic fluid through her lungs (Visembryo 2006). Your baby is immersed in amniotic fluid, which is protecting her as she grows in the amniotic sac.

Sometimes, when you move suddenly, you may a feel a slight pain in your sides. Ligaments on each side of your uterus and pelvic walls are stretching as your baby grows. It's normal to feel some pain, but if it continues for a few days or gets worse, talk to your midwife.

You've probably gained at least 2.2kg/5lb by now, maybe as much as 4.5 kg/10 lb. Your uterus is growing and you might feel pangs caused by the ligaments stretching in your abdomen. These pains are usually temporary but your growing uterus will put extra strain on your back - follow our tips for protecting your back so that you avoid backache.

Many couples worry about what labour will be like and how they'll cope as new parents - it's all perfectly normal. Try chatting to couples with children about how they felt at this stage and read up on what happens in labour. It may help to read some birth stories so you know what to expect too.

It's a good time to arrange a last minute holiday if you can spare the time and money. Travelling in the middle trimester is often recommended because you are usually over the early pregnancy feelings of nausea and fatigue and still not too far advanced for size or premature labour to be a problem. If you are booking now for a flight later in pregnancy make sure your airline will allow you to fly at that stage.