Your baby’s face takes on further definition this week, as the chin and nose become more refined. Week 12 also marks the arrival of fingernails and toenails. Your baby’s heart rate may speed up a few beats per minute. The end of week 12 of pregnany marks the end of your first trimester. As you enter the second trimester, all of your baby’s organs, nerves and muscles are formed and beginning to function together. Growth continues at a rapid pace, but baby is still small at this point.
You can expect to put on about one quarter of your pregnancy weight between now and week 20. You may be beginning to feel more energetic and generally better than during the past few weeks. You should consider telling your employer at this time that you are pregnant. Meanwhile, look at your lifestyle and be sure that your diet includes a sensible range of foods, for you and the unborn baby.
The baby's heart is beating at between 110 and 160 times a minute and its chest is beginning to rise and fall as it practises future breathing movements. Features are becoming more clearly defined and fingers and toes are now fully formed, with tiny nails beginning to grow. The baby can suck its thumb and it swallows amniotic fluid and passes it back as urine. When 12 weeks pregnant, the amniotic fluid is completely replaced every 24 hours. The baby is now about 2.1 inch (5,4 cm) long and weighs 0.5 ounce (14 grams)