Many men prefer to make love without a condom, believing that they can be more intimate with their partner, but at the same time face the risk of unwanted pregnancy. So, many people look to the safe period. The truth is that the safe period is not that safe! The safe period method of contraception is a period of time when a woman is relatively unlikely to conceive, based on her ovulation time and the amount of time that sperm and eggs can survive in the female reproductive tract. Theoretically, if couples make love during this safe period and avoid having sex near ovulation, they can play a contraceptive effect. The safety period can be divided into the pre-ovulatory safety period and the post-ovulatory safety period. The period from the day of menstruation to the start of ovulation is the pre-ovulatory safety period: the period from the end of ovulation to the next menstrual period is the post-ovulatory safety period. The post-ovulatory safety period is safer than the pre-ovulatory safety period because some women are sometimes affected by environmental changes and mood swings, so that the pre-ovulatory safety period will be shortened, and if they have unprotected sex at this time, they may conceive. At the same time, the period after ovulation to the next menstrual period does not usually occur a second time, so the safe period after ovulation is relatively safe. However, if the ovaries ovulate two eggs in one cycle, then the safe period will be impossible to calculate. Although the chance of ovulating twice in a menstrual cycle is very rare, 10% of women still ovulate two eggs in one cycle, and these two eggs may be ovulated together or separately. The safety period is not safe. At the same time, many women have early ovulation or delayed ovulation, so they fall into the “7 before and 8 after” safety period, which is still unsafe. Ideally, the annual failure rate of safe contraception is about 5%, but if there is a slight deviation, such as a wrong algorithm, wrong number, wrong day …… It will lead to contraceptive failure. Therefore, the safety period is really not safe, contraception is not a trivial matter, unsuccessful will become “human”, must not take a chance! References: [1] Chen Yimin, Li Chao. Do you know how to calculate the safe period [J]. Health Expo. 2018(8)