Smelling smoke occasionally during pregnancy may not affect the fetus very much. If you smell smoke for a long period of time, the effect on the fetus may be greater. During pregnancy, if a pregnant woman occasionally smells cigarettes, the toxic substances will be quickly excreted through the body’s metabolism, and generally will not have a significant impact on the health of the pregnant woman and the growth and development of the fetus. If a pregnant woman smells cigarettes for a long period of time, the nicotine, tar and other toxic and harmful substances in the smell of cigarettes may enter into the fetus through the blood circulation of the mother, which may affect the healthy development of the fetus, and may lead to serious consequences such as restricted growth and development of the fetus, abnormal development of the fetus, and fetal death in the uterus. There may also be risks such as preeclampsia and miscarriage. It is necessary for pregnant women to undergo regular pregnancy checkups and make adjustments to their lives in terms of diet and exercise under the guidance of obstetricians and gynecologists.