Smoking and drinking have great adverse effects on pregnancy, which may lead to fetal development malformations, or miscarriage or premature birth, the first trimester of pregnancy is a critical period of embryonic cell differentiation, any external stimulation of adverse factors can easily lead to abnormal differentiation of embryonic cells, causing fetal malformations or miscarriage, whether active or passive smoking, nicotine and carbon monoxide and other harmful substances in smoke can Whether smoking actively or passively, the nicotine and carbon monoxide in the smoke can enter the fetus and affect the normal development of the embryo, especially affecting the liver function of the fetus. Drinking alcohol during pregnancy can also have a significant impact on the fetus, leading to premature birth, miscarriage, fetal growth restriction and fetal neurological deformities.