Development Week 21
You are 21 weeks pregnant and your baby weighs about 13 ounces (360 grams). Your baby is still able to move about inside the amniotic fluid and will only settle down towards the end of this trimester, where it will turn and settle in a head down position.
Growth is starting to slow down and the heartbeat is starting to get stronger. Legs will also be reaching their relative proportions. With the second trimester being the easiest, now is a good time to do things together with your partner, perhaps go away for a weekend or spend some time together.
The amniotic fluid that has cushioned and supported your baby in the uterus now serves another purpose. Your baby's intestines have developed enough that small amounts of sugars can be absorbed from the fluid he or she swallows and will be passed through the digestive system to the large bowel. Almost all of your baby's nourishment, however, still comes from you through the placenta.
Up until now your baby's liver and spleen have been responsible for the production of blood cells. In fact, the fetal liver produces blood cells right up until the time of birth. However,the bone marrow spaces are now developed enough to contribute to blood cell formation as well.
Exercise can be a great way to stay in shape during pregnancy and can even keep some symptoms, such as varicose veins, excessive weight gain, and backache, at a minimum. But pregnancy is not the time to start training for a triathlon - going slowly is the name of the game.
Because ligaments become more relaxed during pregnancy, you're at higher risk for injury, so low or non-impact exercise such as yoga, swimming and walking are your best bets. Talk to your health care provider before beginning any exercise program while you're pregnant.
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