Studies of pregnant athletes have shown that those who were were active throughout pregnancy, but decreased exercise in late pregnancy actually had higher birth and placental weights than athletes who maintained or increased exercise in late pregnancy. The evidence suggests that exercising in mid-pregnancy may stimulate placental growth, which allows for better deliver of oxygen and nutrients to the fetus.
Science also indicates that women who exercise regularly in early to midpregnancy experience a more rapid growth of the placenta and have improved placental function. According to Clapp & Rizk, "at any rate of uterine blood flow, oxygen and nutrient delivery to the baby will be higher in the woman who exercises than in the one who does not."
Just remember to nourish your body with the extra 300 calories needed to sustain all that extra work your body is doing hosting a new life, drink plenty of water (before you feel thirsty), and pay attention to any signs your body may be giving you that you're pushing too hard.
Science also indicates that women who exercise regularly in early to midpregnancy experience a more rapid growth of the placenta and have improved placental function. According to Clapp & Rizk, "at any rate of uterine blood flow, oxygen and nutrient delivery to the baby will be higher in the woman who exercises than in the one who does not."
Just remember to nourish your body with the extra 300 calories needed to sustain all that extra work your body is doing hosting a new life, drink plenty of water (before you feel thirsty), and pay attention to any signs your body may be giving you that you're pushing too hard.