It is a well established fact that smoking reduces sperm quality. Therefore, whether smoking causes infertility is obviously related to the amount of smoking, the duration of smoking, and the original sperm quality. If the amount of smoking is relatively small, occasional smoking, and the original sperm quality is basically normal, it usually does not lead to infertility. However, if you smoke a lot for a long time and your sperm quality is not good, you may face the risk of infertility if your sperm quality continues to decline. Tobacco contains many adverse substances, such as nicotine, tar, carbon monoxide, dioxins, etc. All of these components can have a negative impact on sperm, causing a decrease in sperm count, density, activity rate, malformation rate, and DNA fragmentation. Therefore, men preparing for pregnancy should quit smoking early. Usually quit smoking for more than 3-6 months to gradually reduce the adverse effects of smoking to a relatively low level.