The rate of condoms is not 100%, so wearing condoms for sex can also have the possibility of pregnancy, but the chances of this occurring are small, and may be related to factors such as improper condom use, condom breakage, and unsuitable condom size. If you choose regular condoms and learn to use them correctly, you can play the effect of contraception to a large extent. 1, improper condom use: some men choose to use condoms before they are about to ejaculate, which is not correct, because some sperm exist in the prostate fluid, which may also lead to pregnancy during sex. So it is recommended to use condoms after the erection of the penis and before entering the vagina, which can improve the rate of contraception; 2. Broken condoms: If the condom is of poor quality and breaks when it is used, or if the condom breaks when it is taken off, it may cause pregnancy. It is recommended to check whether the condom is intact before using it and to choose condoms with guaranteed quality; 3, condom size is not suitable: if the size of the condom is not suitable, it may lead to semen flowing out from the gap, which may also cause pregnancy; 4, other reasons: if the condom slips off when having sex, or repeated use of condoms, it may also lead to pregnancy, thus reducing the contraceptive rate. For those who do not have a pregnancy plan, if condoms are found to be broken and other conditions, women need to take oral emergency contraceptive pills to avoid unwanted pregnancy. Although condoms are not 100% contraceptive, they can also reduce the chances of unintended pregnancy to a great extent when used correctly, and more importantly, reduce the risk of contracting sexually transmitted diseases. Therefore, it is recommended to learn the correct way to use condoms so as to avoid unnecessary troubles as much as possible.