Pregnancy is divided into early, middle and late pregnancy, early pregnancy can be appropriate to lie flat to sleep, but into the mid-pregnancy can not lie flat to sleep, because of the adverse effects on the health of the mother and child. Early pregnancy refers to 14 weeks before pregnancy, when the uterus is small, there are not too many requirements for the sleeping position, pregnant women can lie flat or sleep on the side, these positions will not have an adverse effect on the mother and child, it is recommended to choose according to personal habits, as long as it does not affect the quality of sleep can be. After 14 weeks of pregnancy into the middle of pregnancy, the size of the uterus increased significantly, at this time should not lie down to sleep, should be taken to the side to rest. Because when you sleep flat on your back, the enlarged uterus will compress the inferior vena cava, resulting in a decrease in the volume of return blood and a decrease in cardiac output, which can cause a drop in blood pressure and form supine hypotension syndrome. In addition, it can also cause insufficient blood and oxygen supply to the placenta, which can induce intrauterine fetal hypoxia in severe cases. During pregnancy, due to the increase in body load, sleep may be tired, difficult to sleep and other manifestations, before going to bed can be appropriate to use warm water to soak your feet, lying down without contact with electronic products, which will help improve the quality of sleep.