It is not necessary to lie down, but you can also sleep on your side. The position of the gestational sac is mainly related to the location of the fertilized egg, the location of the fertilized egg is low, the position of the gestational sac is also low, before 28 weeks of pregnancy is called the placenta hypoplasia, after 28 weeks of pregnancy the placenta has not grown to the normal position of the placenta is placenta praevia. It is recommended to rest in bed more often, but there is no requirement for women to lie flat, early pregnancy can lie flat, you can also lie on the left and right side of the position, the middle and late pregnancy should not lie down too long, try to choose the left side of the main lying position, lying down too long may cause supine low blood pressure, may not necessarily be beneficial. The lower segment of the uterus is formed around the 16th week of pregnancy, the placenta position will gradually extend in the direction of the uterine fundus, and the position of the fetal sac is likely to rise normally, thus improving the situation of a low gestational sac. During this period, it is necessary to avoid heavy physical labor, and to reduce the action of squatting and waisting and climbing stairs. The downward movement of the position of the gestational sac usually have to do a good job of pregnancy and obstetric examination, there are abnormalities to seek medical attention in a timely manner.