It is very normal for a woman to have her period once a month. Some menstrual cycles are shorter, as short as 21 days, while others are longer, up to 35 days, i.e. 21 days or 35 days between periods, during which it is normal to have a period. Some people have a 28-day menstrual cycle, which is very standard, and this standard menstrual period is usually in the middle of two menstrual periods, about 14 days after ovulation, which is very convenient for both conception and contraception. If menstruation comes once every 2-3 months, we should consider whether there is a problem with ovulation, which needs to be examined in the hospital, there is a disease called polycystic ovary syndrome, which mainly manifests menstrual disorders, as well as ovulation and infertility, and if it is a polycystic patient, we need to come to the hospital to promote ovulation treatment.