Without ovulation, of course, there will be no pregnancy, but ovulation is only a relative time period, not absolute, women through a certain method of their own projection of ovulation is not necessarily the real ovulation. If the endocrine function of the ovary changes due to various life events or habits, it may cause ovulation to advance or push back, in which case there is also the possibility of an unwanted pregnancy after intercourse in the so-called non-ovulatory period. Therefore, this method of contraception through the non-ovulatory period is unreliable, if there is no temporary intention to get pregnant and have children, then it is best to take a safer and more effective contraceptive method of contraception during intercourse, it is not recommended to take the method of contraception in the non-ovulatory period.