The breastfeeding period is the period between breastfeeding and stopping breastfeeding after delivery, usually about six months to a year after delivery. Breastfeeding can inhibit ovulation, so the return of menstruation in breastfeeding mothers is often delayed. Most mothers resume ovulation and menstruation in 4-6 months after delivery, but some mothers will have their menstruation in about 1 month after delivery. The first menstruation is usually preceded by ovulation, and the onset of menstruation is usually half a month after ovulation. Therefore, a breastfeeding mother may have ovulated even though her period has not yet returned, and if she does not take measures to prevent pregnancy, she may become pregnant. For mothers who had their first child by normal delivery, if they are planning to have a second child, it is considered better to have a one-year interval after breastfeeding, and most breastfeeding mothers do not want to have a pregnancy during breastfeeding, so they need to take good contraceptive measures to prevent unwanted pregnancy. For mothers who have had a cesarean section, strict contraception is required for 2 years before another pregnancy can occur. Once the pregnancy is breastfeeding, if the abortion is performed early, there is a risk of uterine damage, infection and subsequent infertility; if the pregnancy continues until the middle and late stages, there is a risk of uterine rupture. There are also very few mothers who have a pregnancy at the cesarean scar, and in severe cases there is a lot of vaginal bleeding and the possibility of hysterectomy. Therefore, mothers who are breastfeeding after a cesarean section should use good contraception. For postpartum mothers suffering from gestational hypertension, gestational heart disease, gestational diabetes and other diseases, they need to continue treatment during breastfeeding and should not be pregnant, some diseases require lifelong contraception, some mothers mistakenly believe that breastfeeding will not be pregnant, once pregnancy, it will aggravate the original disease, increase the risk of abortion, and in serious cases, life-threatening, so it is important to strictly take good contraceptive measures.