Tobacco contains a large number of harmful substances, smoking may make pregnant women lack of oxygen, induced cardiovascular and cerebrovascular diseases, but also easy to cause cancer, the fetus will also have adverse effects. Tobacco contains a large number of harmful substances, such as nicotine, tar, carbon monoxide, etc., long-term smoking is very harmful to pregnant women, may make pregnant women hypoxia, elevated blood pressure and other symptoms, but also may induce cardiovascular and cerebrovascular diseases, in addition, tobacco contains a large number of carcinogens, easy to cause cancer. For the fetus, smoking may make the fetus malformation, intellectual development disorder, and even the occurrence of miscarriage. Whether it is smoking or second-hand smoke, pregnant women should not be exposed to, actively avoid smoke-contaminated environments and stay away from smokers, and undergo regular maternity checkups to ensure the normal development of the fetus.