Most pregnant women take drugs of some kind.
Drugs move from the mother to the fetus primarily through the placenta, the same route taken by nutrients for the fetus' growth and development. In the placenta, drugs and nutrients in the mother's blood cross a thin membrane, which separates the mother's blood from the fetus' blood. A Human studies have shown no risk. B Animal studies have shown no risk but no human studies are available, or animal studies have shown risk but human studies have not. No human or animal studies are available, or animal studies have shown risk but no human studies are available.