There is no specific value for the chances of pregnant women smoking leading to malformations, but according to statistics, the number of congenital malformations occurring in mothers who smoke is two to three times that of non-smoking mothers. Tobacco contains a large amount of nicotine, which can pass through the placenta and then enter the bloodstream of the fetus, which will affect the normal development of the fetus and increase the incidence of congenital malformations. Such as neurological system abnormalities, foot inversion, cleft lip and palate. At the same time, the formation of CO from smoking leads to obstacles in the combination of red blood cells and oxygen, resulting in less oxygen in the blood, causing intrauterine hypoxia in the fetus, resulting in fetal distress and even miscarriage. Early pregnancy is the stage of fetal organ differentiation and development, smoking at this time can increase the incidence of fetal malformation rate, so pregnant women are advised to quit smoking. Pregnant women who smoke should undergo obstetric examination on time, and undergo Down’s syndrome screening and fetal system ultrasound to rule out fetal malformations.