Four months after the birth of a child did not come to menstruation, mainly with breastfeeding, personal constitution, pregnancy and other factors, as follows: 1, breastfeeding factors: during the breastfeeding period, the maternal body will secrete a large amount of lactogen, inhibit estrogen secretion and ovarian ovulation, at this time the endometrium can not shed, so that menstruation can not come. This is a normal physiological phenomenon and normally no treatment is needed. Menstruation will come naturally when the ovarian ovulation function is restored. It should be noted that if the patient is not breastfeeding and has not had her period for four months after delivery, it is recommended to go to the hospital for pelvic ultrasound or endocrine examination to clarify the cause; 2. Personal constitution: the recovery time of menstruation after delivery is related to the maternal constitution, age and other factors. If the mother’s body is weak, blood and Qi deficiency, menorrhagia may appear. At this time, the mother can eat more food rich in nutrients, such as egg custard, milk, etc., appropriate exercise to enhance physical fitness; 3, pregnancy: some people will have extra ovulation even if they do not have a period. During this period, if you have sex without contraceptive measures, you need to consider the possibility of pregnancy. At this time, you can test whether the absence of menstruation after childbirth is related to pregnancy by means of early pregnancy test paper, and if it is clear that you are pregnant, you need to take relevant pregnancy tests in time to ensure that your body meets the prerequisites for another pregnancy.