Amniotic fluid cadmium and thiocyanate in pregnant women who smoke.

About 30% of U.S. women of reproductive age smoke cigarettes. The adverse effects of smoking on the adult population have prompted insertion of the surgeon general's warning on cigarette packages. The effects of smoking on pregnancy and the fetus have been well documented, but the causative agent in "smoke" that produces those adverse effects has not been identified. Cadmium, one of the more toxic materials in cigarette smoke, has been studied in the placenta and maternal blood. To further assess the pharmacodynamics of this agent, we conducted studies to investigate the effect of smoking on the thiocyanate and cadmium concentrations in maternal blood, cord blood and amniotic fluid. Our results showed significantly increased cadmium concentrations in maternal blood and cord blood in pregnant women who smoked (P less than .05) and significantly increased amniotic fluid cadmium concentrations in women who smoked heavily during pregnancy. Maternal and cord blood cadmium concentrations correlated strongly with amniotic fluid thiocyanate concentrations.