Women in the middle of pregnancy can sleep properly lying flat, but it is not recommended for too long, try not to exceed one hour. The middle of pregnancy refers to the 13-27 weeks of pregnancy, when the uterus is not very obvious, pregnant women can choose the appropriate time lying flat, because if too long lying flat sleep, the abdominal wall is likely to compress the fetus, causing the fetus in the uterine cavity lack of oxygen, affecting the normal development of the fetus. In addition, during pregnancy due to the increase of the uterus, the uterus will be mildly right-handed, and the inferior vena cava is also located in the right side of the abdominal cavity, the increased uterus is prone to compression of the inferior vena cava resulting in poor venous return, the reduction of cardiac blood return, pregnant women are prone to supine hypotension syndrome. Between 15-20 weeks of pregnancy, pay attention to Down’s syndrome screening or non-invasive DNA testing, between 22-26 weeks of pregnancy, pay attention to the appointment of 4D ultrasound, do a good glucose tolerance screening and other pregnancy tests at the same time, mid-pregnancy baby bone development is faster, can be appropriate calcium supplementation, eat more bone soup, ribs soup, lean meat, fish and shrimp food.