The ovary of a normal woman of childbearing age expels one mature egg per month, which is discharged into the fallopian tube and usually survives for 1-2 days, while the sperm produced by the man is continuous. Sperm usually remain active in the female reproductive tract for 2-3 days, while their ability to conceive is between 48 hours. If a woman has sex within a certain period of time before and after ovulation, she has the possibility of becoming pregnant. This period is called the “ovulation period”. It is important to master this period because on the one hand, it allows couples who are infertile due to missing the ovulation period to have sex to have a great chance of conceiving; and on the other hand, it allows couples who do not want to get pregnant at the moment to miss the “ovulation period” to have sex without other contraceptive measures in order to prevent conception. Common methods of calculating ovulation include: 1. cervical mucus observation method (must be done in a hospital). 2. 2. Basal body temperature measurement method. Both: The body temperature measured when the body wakes up after a long sleep (usually in the early morning), before any activity and speech, is the basal body temperature. Under normal circumstances, the basal body temperature of women of childbearing age is low during the first half of menstruation and even lower during ovulation, and can rise suddenly or slowly by 0.3-0.6°C within 24 hours to a few days after ovulation. Therefore, it is best to measure the basal body temperature from the first day of menstruation and insist on measuring it every day, and record it with coordinate paper for observation and analysis. 3.Menstrual date projection method. Both: It is believed that each ovulation should be about 14 days before menstruation, so 5 days before ovulation – 5 days after ovulation is called “ovulation period”. However, this method is not very reliable because most women do not have regular menstruation. In contrast, the first two methods are more reliable, but somewhat cumbersome. Here we would like to introduce you to a simple and more reliable method of calculating ovulation, which we hope will help you. The formula for calculating the ovulation period is: First day of ovulation = days of the shortest menstrual cycle minus 18 days. The last day of ovulation = the longest menstrual cycle minus 11 days. Before using this formula, I was asked to observe and record my menstrual cycle 8 times in a row to get the longest and shortest days of my menstrual cycle, and the numbers obtained by substituting the above formula indicate the beginning and end of the woman’s “ovulation period” respectively. (The menstrual cycle is calculated from the first day of the current menstrual period to the first day of the next menstrual period.) For example, if a woman of childbearing age has had a maximum of 30 days and a minimum of 28 days in her first 8 months of menstrual cycle, the formula is: First day of ovulation = 28 days – 18 days = 10 days. Last day of ovulation = 30 days – 11 days = 19 days. In other words, this woman’s “ovulation period” begins on the 10th day of her current period and ends on the 19th day of her current period. If you observe that your menstruation is very regular: once every 28 days, then you can set the longest and shortest days of your menstrual cycle as 28 days and substitute them into the formula to calculate your “ovulation period” as the 10th-17th days of your current menstrual cycle. This method of calculating the ovulation period is based on the first day of the current menstrual period and counting backwards in days, instead of counting backwards in days based on the next menstrual period, so it is not easy to get it wrong. After finding out the “ovulation period”, if you want to get pregnant, you can have intercourse every other day from the first day of the “ovulation period” for several months, and you will most likely get pregnant. If you don’t want to get pregnant, you have to miss the “ovulation period” and have sex.