A normal woman regularly discharges 1 egg every month and has to go through the process of follicle development → ovulation → conception or dropping into menstruation like this, a process that takes about 28~30 days. Dangerous period: Ovulation day is about 14 days before menstruation, the egg can survive for 1~2 days after discharge, and the sperm can be latent for up to 5 days after entering the vagina! Therefore, a total of 7 days before and after the “ovulation period” is relatively easy to conceive, and for those who do not want to get pregnant, it is the “danger period”. Safety period: So the “safety period” is the period when the eggs are not ripe or old, which is the two ends of the ovulation period, so mastering the “ovulation period” is the way to go. The reality is that people will take menstruation as a benchmark for easy estimation, using “7 before and 8 after” or “4 before and 5 after” to simply calculate, very easy to deviate. The basis of the safe period method is that there are some differences between women’s bodies during the ovulation and non-ovulation periods, and based on these differences, they can determine the ovulation period and avoid it, so that the egg and sperm have no way to meet, and pregnancy can be avoided. However, the first three and then four, the first seven and then eight and so on, are too simple and crude, and not scientific, how to effectively project the safe period, we have three methods. 1, the calendar method The calendar method, as the name implies, is to create a calendar in which to mark which days are ovulation and which days are the safe period. The accuracy of this calendar should be based on accurate observation for at least a year, during which time hormonal types such as birth control pills, especially short-acting contraceptives, should not be used. After taking short-acting contraceptives the menstrual cycle is all 28 days, but that is not your own cycle, it is the cycle established for you by the pill. How do I create this calendar table? The number of days between counting the first day of your period as the first day of your cycle and the day before your next period is due is a full cycle. The duration of each cycle may be different, a short one maybe 25 days, a long one maybe 33 days, and you have to mark it as such. The beginning of ovulation is calculated by the shortest menstrual cycle, by subtracting 18 days from the shortest menstrual cycle days. For example, if you have a 25-day menstrual cycle, after subtracting 18 days, ovulation begins on the 7th day. The end of the ovulation period is calculated by the longest cycle, subtracting 10 days from the longest cycle. For example, if your menstrual cycle is 33 days, after subtracting 10 days, then you enter the safe period from the 23rd day. However, even for women with very stable menstrual cycles, their ovulation and menstrual timing can still be affected by many factors, such as ill health, elevated stress levels, too much fatigue, and emotional changes that can cause them to ovulate and delay their periods early or late. For those women whose cycles are inherently unstable, the calendar method is even more fraught with risk. 2. Cervical mucus method The cervical mucus method requires women to be able to recognize the differences in vaginal discharge at different times, mainly in terms of volume and texture. Take a menstrual cycle as an example: the days just after menstruation, when there is no vaginal discharge or it is extremely sparse and usually invisible, are considered safe. When thick, white, yellow mucus is noticed, estrogen rises, follicles tend to mature, intercourse is no longer safe, and other contraceptive measures should be used. In a few days, the mucus will become as clear as egg white. Take a bit of mucus between your thumb and forefinger and stretch it, you will find that it is full of elasticity and can be pulled out in a silky way. At this time, when you probe your finger into the vagina, you will feel that it is moist and warm. When the body starts to secrete thick white and yellow mucus again, ovulation ends and after 24 hours of secretion, the woman enters the safe period again. This method is less workable for women with low congenital mucus production. When an infection occurs in a woman’s reproductive system, it affects the amount and texture of the mucus, and the cervical mucus method can easily fail at this time. In addition, this method requires reliable guidance and a longer learning period, and do not use unprotected intercourse during the first observation cycle. 3. Basal body temperature method The basal body temperature method is often used by pregnant mothers, and its use for contraception is based on the same principle: before imminent ovulation, the basal body temperature (body temperature at rest when waking up in the morning) will drop slightly, and after ovulation occurs, the corpus luteum begins to release more progesterone and the body temperature will rise slightly by about 0.2 to 0.5°C. Pregnant mothers will take advantage of this time to make a baby with their expectant dads, while women on birth control will want to abstain from sex or use more efficient birth control at this time. To use the basal body temperature method, it is important to test your basal body temperature during at least one menstrual cycle. Since basal body temperature changes are slight, women need to use a sensitive and precisely graduated thermometer. Note: Using it in combination with the calendar method, the cervical mucus method, and the basal body temperature method increases its accuracy, whether for pregnancy preparation or contraception. However, it has to be suggested that as a contraceptive method, it is always too cumbersome and has a high failure rate and is not recommended.