If you wear condoms for a long time and use them correctly, the chance of pregnancy is almost 0, because the contraceptive effect of condoms is very good, but it may lead to pregnancy in the following cases: 1. If the condom slipped out during the use of the condom, a large amount of semen will enter the vagina, which may also lead to pregnancy; 3. Although the condom did not slip out during the use of the condom, but there is a breakage, then even if there is a small hole, the semen will enter the vagina and enter the fallopian tube to form a fertilized egg. Therefore, the correct use of condoms is very critical, and it is also recommended that the entire process of sex in general condoms contraception.