Stretch marks usually fade naturally about 3 months after delivery, but there is some variation among patients. Stretch marks mainly refer to a kind of pigmentation formed during pregnancy due to the change of hormone level in the body, which leads to the increase of melanin on the face. With the birth of the child, the hormones in the body gradually return to the pre-pregnancy level, and at this time, the hormone level in the body is stable and will not continue to affect the melanin cells in the body. It should be noted that before the stretch marks fade completely, you should avoid direct sunlight for a long time, otherwise the frequent stimulation of ultraviolet rays will easily lead to the aggravation of stretch marks and prolong the self-healing time.