The week before menstruation is a safe period because a woman’s ovulation period is 14 days before her next menstrual period. This time is fixed, regardless of the length of the menstrual cycle, because this period is medically called the luteal phase, and the luteal body is maintained for 14 days, so the week before menstruation is a safe period. However, sometimes the safe period for a very small number of women is not safe, because there is a kind of extra ovulation in the clinic, and if a woman has some accident during this period, or if she is emotionally stressed or excited, it can lead to abnormal ovulation. Therefore, it is best for women to use contraception every time they have sex if they do not want to get pregnant.