Occasional smelling of cigarette smoke by pregnant women usually does not affect the fetus, but if smelling cigarette smoke for a long period of time, it may affect the fetus, such as fetal malformation, intrauterine fetal death, spontaneous abortion, and so on. 1. Fetal malformation: The smell of cigarette smoke contains a large amount of nicotine, if inhaled for a long time, especially in the early stages of pregnancy, it may lead to fetal malformation. 2. Fetal intrauterine death: frequent smoking odor in mid-pregnancy may lead to intrauterine asphyxia, because a large amount of cigarette smoke will lead to a decrease in the oxygen content of the placenta, and the fetus will not be able to take in the oxygen it needs, and intrauterine death will occur. 3. Spontaneous abortion: pregnant women inhale a lot of smoke, may also lead to a reduction in the secretion of progesterone, resulting in pregnancy termination, induced spontaneous abortion. So it is recommended that pregnant women do not smell smoke during pregnancy, if the pregnant woman smells smoke after the discomfort of the symptoms suggest timely medical attention, under the guidance of the doctor to improve the relevant examination, clear cause of the symptomatic treatment.