Patient's question:
How is the so-called safe period calculated?Doctor's answer:
The method of calculating ovulation based on the menstrual cycle is also known as the calendar method. Both menstruation and ovulation are influenced by endocrine hormones from the pituitary gland and ovaries, exhibiting cyclical changes. The lengths of both cycles are consistent, occurring once per month, with ovulation occurring between two menstrual periods. A woman's menstrual cycle can vary in length, but the interval between the day of ovulation and the start of the next menstrual period is relatively fixed, generally around 14 days. Based on this relationship between ovulation and menstruation, it is possible to calculate the ovulation period based on the menstrual cycle. The calculation method starts from the first day of the next menstrual period, counting backward 14 days or subtracting 14 days to determine the day of ovulation. The day of ovulation, along with the 5 days before it and the 4 days after it, together constitute the ovulation period. This is the theoretical basis for the safe period method of contraception. For example, if a woman's menstrual cycle is 28 days long, and the first day of her current menstrual period is December 2, her next menstrual period will occur on December 30 (December 2 plus 28 days). Subtracting 14 days from December 30 gives December 16 as the day of ovulation. The ovulation period, which includes the day of ovulation and the 5 days before and 4 days after, is from December 11 to December 20. Except for the menstrual period and the ovulation period, all other times are considered the safe period.