Stretch marks are generally formed in the late stages of pregnancy (after 28 weeks), with the gradual increase in the size of the uterus, the tension of the abdominal wall increases, and the rectus abdominis muscle and skin fibers are separated and broken texture. It occurs in the vast majority of women. Stretch marks are red during pregnancy and turn white after delivery. The reason for the absence of stretch marks, on the whole, is mainly the fact that the rectus abdominis muscle, the skin of the abdomen is very elastic, and there is no separation of the muscles, as well as breakage. It also indicates that it may be due to the small size of the fetus and low tension. Pregnant women who are generally on the younger side of the age range and who enjoy sports and long-term exercise have better organism performance and tend not to develop stretch marks. This is a good phenomenon, the absence of stretch marks during pregnancy is conducive to the recovery of body shape after delivery.