Low placenta may grow up, but not absolutely, some pregnant women will develop placenta praevia. Before 28 weeks of pregnancy check the placenta position is relatively low for the placenta low state, with the increase of pregnancy weeks and uterine enlargement, the placenta area occupies a smaller proportion of the uterus, the placenta position will gradually upward traction, but not absolutely. After 28 weeks of pregnancy, the lower edge of the placenta is <2cm from the endocervical os, it is called placenta praevia, after 28 weeks the placenta generally does not continue to grow upward, during pregnancy, we should be vigilant about the possibility of preterm delivery and hemorrhage. Pregnant women who check the placenta after pregnancy, usually to minimize squatting or lower back movements, do not do too heavy physical labor work, prohibit sexual intercourse, pay attention to nutritional supplements, conducive to the development of the fetus.