There are several ways to know ovulation: 1. When the ovulation test is positive, a weakly positive change in the test again will prove ovulation. 2. If there are no more mature follicles on the ovaries, it proves that ovulation has occurred. The survival period of the egg is within 48 hours after ovulation, so the woman has a higher chance of getting pregnant during this period. The other time is the safe period, when no egg is released and the woman cannot get pregnant even if she has intercourse. Therefore, this method can be used to determine a woman’s ovulation status and choose the appropriate contraceptive method or conception method.