Smoking during pregnancy can be harmful to both the pregnant woman and the fetus, so from a health perspective it is not recommended for pregnant women to smoke, even one cigarette a day. About the adverse effects of smoking on pregnant women and fetuses may have the following: 1, the impact of smoking on the pregnant woman itself: because the nicotine in the cigarette has the effect of constricting blood vessels, after smoking the blood flow of pregnant women will be reduced, may cause a series of cardiovascular and cerebrovascular diseases such as gestational hypertension; in addition, the tar and carbon monoxide in the smoke into the respiratory tract will also cause bronchitis, pneumonia and other respiratory diseases In addition, continued heavy smoking during pregnancy may lead to miscarriage and premature birth; 2, the impact of smoking on the fetus: nicotine and benzopyrene in cigarettes affect the quality of mature egg cells, continued heavy inhalation will make the uterus less receptive to the fetus, but also cause impaired blood circulation in the uterus, resulting in a series of adverse effects on the fetus such as hypoxia, stunted growth, malformations, premature birth and even stillbirth. This can lead to a series of adverse effects, such as hypoxia, hypoplasia, malformation, preterm delivery and even stillbirth. For the health of the pregnant woman and the normal development of the fetus, in addition to the pregnant woman to prohibit smoking, family and friends should also try to reduce smoking to avoid second-hand smoke or third-hand smoke on the pregnant woman and the fetus caused harm.