Answer
Smoking is inimical to the health of the fetus especially during the early stages of pregnancy. For the smoking mother the smoke is what is most harmful. For the fetus it is the nicotine in the mother's that is most dangerous.
Work Step by Step
Nicotine is a teratogen that can cause fetal congenital abnormalities. It hinders oxygen delivery to the fetus, and negatively impacts growth and development. In addition, nicotine is a strong toxin that induces vasoconstriction; it damages the tunica of blood vessels and interferes with the regulation of arteriolar diameter.