What is the ovulation period and safety period?

A woman's menstrual cycle usually lasts from 28 to 35 days. The number of days in each month is different, but the dates of each month are usually the same. A woman's menstrual cycle can be divided into three phases: before intercourse, in between and after intercourse.

Previous intercourse refers to the first sexual intercourse between a woman and her partner and is also the first stage in a woman's menstrual cycle. During this stage, a woman's hormone levels change, which may affect her fertility.

Interphase refers to the second phase in a woman’s menstrual cycle, also known as the danger period. During this stage, a woman's hormone levels reach peak levels, which may lead to pregnancy.

Post-sex intercourse refers to the third phase of a woman’s menstrual cycle, also known as the safe period. During this stage, a woman's hormone levels drop, which may or may not lead to pregnancy.

However, a woman's menstrual cycle is not completely accurate and can sometimes fluctuate for a few days. Therefore, when calculating a woman's menstrual cycle, it can only be based on the usual cycle.