You can have children after 3 months of quitting smoking. Tobacco is harmful to the human body, tobacco contains a large number of carcinogenic substances that can cause mutations in key genes in the body, leading to cell carcinogenesis and malignant tumors, tumors related to smoking include lung cancer, nasopharyngeal cancer, laryngeal cancer, esophageal cancer, stomach cancer, etc.. Smoking can also cause endothelial damage to blood vessels, leading to the development of atherosclerosis, resulting in narrowing of the arteries, which affects blood flow and causes cardiovascular disease. Clinically, smoking is the biggest cause of coronary heart disease, and quitting smoking can significantly reduce the incidence and risk of death from coronary heart disease, arterial vascular disease, and sudden cerebral death. Smoking can also cause reproductive system and fetal development abnormalities.