Your pregnancy at week 12

Welcome to your week 12 pregnancy update where we outline the changes you and your baby are experiencing.

Your baby

Your baby has been very busy in the past few weeks. At week 9 she weighed around 2 grams and now at week 12 could be weigh anything between 18 and 30 grams! His eyes have moved from the sides to the front of his head, and his ears are right where they should be. The placenta is still larger than the baby at this stage, and will be supplying baby with oxygen, fats, proteins, vitamins and minerals. The placenta will also filter out carbon dioxide and waste materials, in an intricate process called ‘diffusion’.

Your baby is also actively rehearsing ‘breathing’ by inhaling and exhaling amniotic fluid to prepare the lungs for future air respiration. Baby’s poo is also building up in his intestine, waiting to be released once he is born in a tarry, dark substance called meconium.

Baby is wriggling, moving and waving around in the amniotic fluid, which remains at a nice 37.5 degrees Celsius, which is slightly higher than your body temperature.

Just like adults, all babies are different and develop at varying rates in the womb. This information gives a general idea of your baby’s development and progress.

The Mum Update

Your uterus is remarkable – during pregnancy, it grows upward to fill the pelvis and abdomen, and returns to its normal, pre-pregnancy size within a few weeks after delivery. Up until now your uterus (and baby) have been hiding down in your pelvis but by the end of week 12, your uterus is peeking above your pubic bone (you might be able to feel it).

Before pregnancy, your uterus is almost solid. It holds about 10ml or less. The uterus changes during pregnancy into a comparatively thin-walled, muscular container big enough to hold the foetus, placenta and amniotic fluid. The uterus increases its capacity 500 to 1000 times during pregnancy! During the first few months of pregnancy the utertine growth is due to hormonal stimulation by estrogen and progesterone. Later in pregnancy, the growth of the baby and the placenta stretch and thin the uterine wall.

The weight of your uterus also changes. When your baby is born, your uterus weighs almost 1.1kg compared to 70g before pregnancy.

Week 12 can mark the start of a calm and well period for many women. Signs of tiredness and morning sickness are starting to subside. However, around 15% of women continue to feel nauseous (or vomit) until 20 weeks of pregnancy, or even beyond this time. You don’t need to continue with folic acid supplements any longer

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