Ovulation in women usually occurs around the 14th day before the next menstrual period, according to this, 4-5 days before and 4-5 days after ovulation is the fertile period, and the rest of the time is called the safe period. This method is suitable for women with particularly regular menstrual cycles. For women with irregular menstrual cycles, there is no way to calculate this method, and women with safe periods are not safe. Because women’s ovulation is affected by a variety of factors, such as women’s recent nervousness, emotional fluctuations, or stressful life, work, study, or recent irregularities in life and rest, may cause women to ovulate early or later wrong, in this case choose the safe period of contraception, but it is not safe.