How long it takes to menstruate after having a baby is related to factors such as the mother’s physical fitness, the way she breastfeeds, and the length of time she breastfeeds, so the exact time varies from person to person and cannot be generalized. Menstruation is a process of cyclical thickening and shedding of the uterine lining, which is affected by hormone levels in the body. During breastfeeding, the body produces a lot of lactin, which inhibits the secretion of estrogen and also inhibits the proliferation of the endometrium, leading to a delay in the recovery of menstruation, so most women will resume menstruation about 6 months after giving birth, and the longer the breastfeeding time, the later the menstruation will resume. The longer the breastfeeding period, the later the return of menstruation. Some mothers do not resume menstruation during the entire breastfeeding period, and menstruation resumes only after breastfeeding is over, when the body’s level of prolactin decreases and estrogen and progesterone gradually return to normal. In addition, although menstruation does not resume after childbirth, if you have sex at that time, you should still take appropriate contraceptive measures.