How to calculate the menstrual safety period on the 9th

If a woman's menstrual cycle is regular, the safe period can be calculated according to the ovulation day 14 days before the next menstrual cycle. If the menstrual cycle is 30 days, the ovulation day 23 days, the risk period 4 to 5 days before and after, and the rest of the time is the safe period. The safe period does not mean that the woman will not be pregnant during this period. Women who do not plan to prepare for pregnancy also need to take contraceptive measures.