“Honey, did you bring the TT?” “Oops, I ran out. It’s okay, don’t you have a few more days before your period? Don’t worry, I’ve done all the math, seven before and eight after, absolutely safe!” I don’t know how many people have experienced such a dialogue scene. The “seven days before and eight days after” has become the rule of birth control that many people believe in, that is, the first seven days of a woman’s period and the last eight days after her period are safe. This widespread theory has caused many ignorant men and women to suffer. So, how many days before a woman’s period is a safe period? Which day in January is safer? When it comes to the safety period, many people may not know that the safety period is divided into pre-ovulatory safety period and post-ovulatory safety period. The so-called pre-ovulatory safety period refers to the period from the first day after menstruation until the start of ovulation, while the post-ovulatory safety period refers to the period from the day after ovulation to the last day of the menstrual cycle. It is worth noting that the post-ovulatory safety period is generally considered safer than the pre-ovulatory safety period, which means that the days before menstruation are relatively safer. This means that the days before menstruation are relatively safer because, at this time, the day of ovulation has already passed, so the chances of pregnancy are smaller. Women can determine the average number of days of their menstrual cycle based on the previous 6-12 months of menstrual cycles and budget the date of their next menstrual cycle, which is usually 28 days; the expected date of the next menstrual cycle minus 14 days is the presumed ovulation date; the 5 days before and 4 days after the presumed ovulation date (10 days in total) is the danger period. If Lili has her period on the 1st of this month and her period ends on the 6th, then Lili’s ovulation day is the 14th of this month, of which 9-18 days is the danger period; 7-8 days is the pre-ovulation safety period, and the week before her next period, which is 19-27 days, is the post-ovulation safety period. So, which are the safer days of the month for women? In fact, the first 3 days of menstruation are relatively safe. The sperm survival time is usually around 1 to 3 days, so by the time you ovulate, the sperm may not exist anymore, which can greatly reduce the chance of pregnancy. However, it is still recommended that you should choose other, more reliable methods of contraception, because the chances of failure with a safe period contraception are very high! References: [1] Chen Yimin, Li Chao. Do you know how to calculate the safety period [J]. Health Expo. 2018(8)