Men smoking three cigarettes a day has an impact on pregnancy preparation. Tobacco contains a lot of harmful substances that not only affect the respiratory system, but also have a very strong impact on the reproductive system. It will affect the sperm activity rate, so that the fertilization rate is reduced, and in many cases, due to excessive tobacco intake, it will affect the probability of conceiving a baby, resulting in a long time can not be conceived. Excessive tobacco intake over a long period of time can affect the intrinsic quality of the sperm, affecting the integrity of the sperm DNA, not only the problem of not being able to conceive a baby, but may also affect the health and quality of the baby that is conceived. In order to ensure eugenics, be sure to quit smoking before preparing for pregnancy, spermatogenesis cycle in about 3 months, it is recommended to quit smoking 3~6 months before starting to prepare for pregnancy.