Stretch marks do not need to be treated. A stretch mark is a light brown vertical line that appears in the center of a woman’s abdomen after she becomes pregnant. The formation of this vertical line usually occurs after the fourth month of pregnancy and becomes more and more obvious as the number of months of pregnancy increases. The reason for the appearance of stretch marks is mainly related to the changes in the level of sex hormones in the body after pregnancy, resulting in localized hyperpigmentation. The length of the stretch marks, as well as the depth of the pigmentation, varies from woman to woman during pregnancy. These stretch marks usually fade after full-term delivery, and most of them will disappear after 6-12 months after delivery. Mothers can take appropriate vitamin C and vitamin E supplements, which are beneficial to the fading of stretch marks.