Extracorporeal spermatozoa is not an effective form of contraception and is generally only about 60-70% effective. The combination of IVF and safe period contraception will increase the effectiveness rate, and can generally achieve safe contraception, but there is also a risk of pregnancy. Ovulation occurs in the middle of two menstrual periods, and one week or five days before and after ovulation is the fertile or relatively dangerous period, when the ovaries may ovulate at any time. The rest of the time is relatively safe, so the relative safe period mainly includes the first week and the last week of the menstrual cycle. In the relatively safe period of intercourse, if the combination of external spermatozoa can generally be effective contraception, and in the relatively dangerous period of intercourse if only the use of external spermatozoa, this method is generally not very reliable, this time more recommended condom contraception, contraceptive pills or contraceptive rings and so on.