When used correctly, condoms have a 99% success rate in preventing pregnancy. This is because the condom can completely block the sperm inside the condom, and the sperm will not flow into the woman’s vagina. Only in some cases when the quality of the condom is faulty, broken, or when the condom falls off after intercourse, will sperm spill into the woman’s vagina, and the woman will have the possibility of conception. However, the chances of this happening are very low, so the chances of using condoms to prevent pregnancy are very high. If the condom is not used correctly, for example, if the condom is not used for the entire period of contraception, and if the condom is not checked after contraception to make sure that it is not torn or has fallen off, the effectiveness of contraception in this case will be greatly reduced. Depending on when the patient has intercourse, such as during the safe period or during ovulation, the failure rate of contraception is different in different cases.