A Chinese article titled Women’s Ovulation Period and Safe Period

A woman's safe period and ovulation period are determined based on a woman's menstrual cycle. Generally speaking, a woman's menstrual cycle lasts 28 days, so starting from the 14th day of the menstrual cycle, a woman's safe period will begin. This period refers to days 14 to 23 of the menstrual cycle. This period is safe because the woman will not release an egg and will not become pregnant.

However, not all women will follow this cycle, so we need to judge a woman’s safe period and ovulation period based on her menstrual cycle. If a woman's menstrual cycle is short, the safe period will be relatively long; if a woman's menstrual cycle is long, the safe period will be relatively short.

A woman's safe period and ovulation period are not fixed, but depend on her menstrual cycle. Therefore, if a woman is unsure about her menstrual cycle, it is best to consult a doctor or calendar.