How to calculate the safe period of contraception

Safe period contraception, this must be a patient with a regular menstrual cycle, who can grasp the safe period and the ovulation period, but this success rate is not very high. The general contraceptive success rate is 80%, and 20% of people will fail. Because Ovulation is also affected by emotions and the environment, it will also show that ovulation is advanced or delayed. This ovulation period is generally about 14 days before the next menstruation, the surrounding three to five days are the ovulation period, and the other times are the safe period. Therefore, if the patient with regular menstrual cycle can master this period, the patient with irregular menstrual cycle, then there is no way to calculate ovulation period, safety period, this time you need to go to the hospital to do color ultrasound, with ovulation test paper monitoring, you can master your ovulation period or safety period.