It is a popular rumor that after a mother has her period, her breast milk becomes “fetal flower milk” and the nutritional content is greatly reduced and has no nutritional value. Is this true? In fact, this is a misconception. The recovery time of the postpartum period varies from person to person, while the composition of breast milk changes in its own time pattern. The whole breastfeeding milk can be divided into three stages, colostrum, transitional milk and mature milk. Colostrum has less fat and more protein, transitional milk has a decreasing protein content and a higher fat content, mature milk has even lower protein content, but it is rich in fat, carbohydrates, vitamins and minerals, and the calcium and phosphorus ratio is more suitable for the little baby in this period. This is a natural change in the law of breast milk and is not directly related to the return of menstruation. Also this change is in line with the needs of the baby at different stages of physiological development. So the old saying that milk after menstrual transition has no nutritional value is too one-sided. Therefore we recommend to insist on breastfeeding even if you turn menstrual, and not to give up the best food for your baby because of ignorance. During breastfeeding, the most important thing is to prevent the occurrence of acute mastitis. On the one hand, keep the milk flowing smoothly, as much as possible bilateral feeding rotation, do not retain too much milk; on the other hand, keep the nipples clean to prevent bacterial retrograde infection after the baby bites the nipple. Once the milk accumulates, swelling and pain, and even with general fever, go to the hospital for active treatment.