Despite the pronounced metabolic changes (221), there is a paucity of experimental and clinical research on pregnant and lactating women in drug metabolism (222–224), hence their designation as therapeutic orphans (37). Indeed, most research has focused on the health risks for the nursing infant, not the mother (225). During pregnancy, alcohol ingested by the mother, along with its toxic metabolites, can cross the placental barrier into the fetal bloodstream and amniotic fluid, which the fetus swallows. The fetus can excrete alcohol via a) placental clearance back to the maternal blood flow and b) urinary excretion into the amniotic fluid or oxidate it (although at a much smaller fraction than the mother) by ADH and ALDH (226).
