Seven lives and eight lives are not "is also a popular saying. It means that once the pregnancy is premature, the premature baby born at 7 months can survive, while the premature baby born at 8 months is not easy to survive. In fact, anyone with a little medical knowledge should be able to see that this statement is wrong. The development of human body begins with the combination of sperm and egg, and with the passage of time, the embryo gradually matures. It first split from single cell to multi-cell, and it took 2 months to form. After that, the tissues and organs will further develop and their functions will be further improved. By the seventh month of pregnancy, the lungs of the fetus have already had the basic respiratory function, which is also the basic condition for the survival of newborns, but the vitality is very weak and the survival rate is very low. At the eighth and ninth month of pregnancy, the fetus grows very fast, with a body length of 40-50 cm, rapid weight gain, gradually full subcutaneous fat, loud crying after birth, strong vitality and great possibility of survival. Therefore, the longer the pregnancy, the more perfect the fetal development. Therefore, a baby who is pregnant for 8 months may be bigger and easier to raise than a baby who is pregnant for 7 months.