You can’t smoke when you’re pregnant. Women are not allowed to smoke during pregnancy preparation and pregnancy, smoking is harmful to the pregnant woman herself, and will also cause greater harm to the fetus. Tobacco contains a large number of harmful substances, including nicotine, hydrocyanic acid, carbon monoxide, tar and so on, these harmful substances can pass through the blood circulation of the placenta from the mother to the fetus. These harmful substances can cause embryonic abnormality or even miscarriage in early pregnancy, and may also lead to fetal hypoxia, slow growth and development in middle and late pregnancy, or even lead to fetal developmental deformities. Therefore, smoking should be absolutely prohibited during pregnancy and second-hand smoke should be avoided. In addition, you should supplement nutrition and exercise properly to ensure the healthy development of the fetus.