Last menstrual period and ovulation

There are two important time points in a woman’s menstrual cycle: the last menstrual period and the ovulation period. Last menstrual period is the first day of a woman's last menstrual period, usually on the same day each month. Ovulation refers to the time when a woman's eggs are released from the ovaries into the fallopian tubes, usually starting 14 days after her last menstrual period.

A woman's menstrual cycle is affected by many factors, including genetics, hormonal levels, lifestyle and health. Therefore, every woman's situation is different. However, generally speaking, the last menstrual period and ovulation period are fixed in a woman's menstrual cycle.

How to calculate ovulation

To calculate a woman's ovulation period, she needs to know the first day of her last menstrual period and the number of days in her cycle. Cycle days can be determined by calculating the time from the first day of the last menstrual period to the first day of the next last menstrual period.

For example, if the first day of your last menstrual period is January 1, 2022, the cycle length is 28 days. If the first day of her next last menstrual period is February 15th, then a woman's ovulation period is February 1st plus or minus 14 days, which is February 8th plus or minus 14 days.

The calculated dates are only an approximate time frame, as a woman's menstrual cycle is affected by many factors. If a woman has a shorter cycle, she may ovulate earlier, and vice versa.

Things to note

A woman's menstrual cycle and ovulation are affected by many factors, so it is impossible to accurately predict a woman's ovulation.