Sleeping on the right side at the beginning of pregnancy has no effect on the fetus, but sleeping on the right side for a long time in the middle and later stages of pregnancy will have a certain effect on the fetus. At the beginning of pregnancy, because the fetus is relatively small, the pregnant woman’s uterus is relatively small, sleeping on the right side will not affect the development of the fetus, pregnant women can choose their own comfortable position to rest, as long as to avoid pressure on the abdomen can be. But with the gradual development of the fetus, the uterus will also increase, to the middle and late pregnancy when the uterus right, if this time to take a long time to rest on the right side of the position may compress the abdominal aorta, is not conducive to the arterial blood circulation, affecting the blood supply of the placenta, easy to lead to intrauterine ischemia, hypoxia, which can endanger the healthy development of the fetus. It is generally recommended that in the middle and late stages of pregnancy, you should try to rest in the left lateral position, which can ease the right rotation of the uterus and improve the blood supply to the placenta, which is conducive to the development of the fetus. However, it is not the only way to take the left side of the pregnancy, do not need to force a fixed position, occasionally the right side of the rest can also be avoided for too long, to reasonably adjust the sleeping position.