Weekly Guide to Pregnancy: Week 12

Week 12
Week 12 

Your Baby

How big is my baby?

Your baby is approximately 60mm (2.5 inches) in length and weighs between 9 and 14 grams (0.3-0.5 ounces). The baby is moving about a lot but is still too small for you to be aware of the movements.

From this week onwards your baby is recognisable as a human being and is now called a fetus as opposed to an embryo. Now, or close to this time, you should be able to hear your baby's heartbeat with a Doppler (a special listening device).

The fingers and toes develop, and nails and teeth are beginning to form. The skeletal system, which began developing earlier, now has centres of bone formation (ossification) in most bones. The external genital organs are growing. The amount of amniotic fluid is increasing.

The nervous system has continued to develop, and the digestive system is now capable of making the contractions that process food.

Your Pregnancy

 The end of week 12 marks the end of the first trimester of pregnancy.

Nuchal fold / nuchal translucency screening - this is an ultrasound screening assessment to detect a specific abnormality of the fetus that can be linked to Down's Syndrome. Nuchal fold / translucency screening is usually performed between 11 and 13 weeks and is becoming more routine. It is a fairly reliable, non-invasive way of assessing the risk of having a baby with Down's syndrome, and carries no risk of miscarriage. The test is conducted by measuring the appearance and amount of fluid that normally accumulates under the skin at the back of your baby's neck. The fluid accumulation tends to increase when the fetus has a chromosomal disorder. The pick-up rate is thought to be 70-80%, depending on your age.

At this point in your pregnancy you may start to notice signs that morning sickness is improving and will begin to feel much better. There will be a thickening of your waist as the fetus starts to move out of the pelvis. Your breasts may also be getting larger, and will most likely have been tender and sore for some time. It is not uncommon to experience an increase in soreness of the nipples too. You may also gain some weight in your legs and at your sides. For the first 12 weeks of pregnancy a weight gain of between 1.8-3.6 kg (4-8 pounds) is normal.

Haemorrhoids are a common disorder of pregnancy. They are usually caused by an increase in the hormones oestrogen and progesterone, and can later be affected by an increase in blood volume and the pressure of the uterus on the pelvic floor. Constipation during pregnancy and prolonged bearing down during birth are the main factors that aggravate haemorrhoids. To prevent constipation during pregnancy, eat a diet that is high in fibre and drink at least 6 to 8 glasses of water per day. Haemorrhoids will probably improve after pregnancy and birth, but they may not go away completely. Talk to your health care professional about the treatment method that is best for you.

Learn more about your pregnancy

Read more information on Pregnancy and Birth on Essential Baby.

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The First Trimester

4 weeks pregnant
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12 weeks pregnant

The Second Trimester

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The Third Trimester

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