Effects of delta-9-tetrahydrocannabinol, chlordiazepoxide (Librium), and their combination on pregnancy and offspring in mice [correction of rats].

Delta-9-tetrahydrocannabinol (THC), chlordiazepoxide hydrochloride (Librium) or a combination of these drugs, were administered to pregnant mice on gestation days 6 to parturition. Levels of THC in blood were dose-related and approximated levels attained in humans after smoking one to two marijuana cigarettes. Blood cannabinoid levels in mice were elevated by concurrent administration of chlordiazepoxide. Maternal weight gain was significantly reduced by THC but not by chlordiazepoxide. Neither drug affected implantations, but THC significantly increased resorptions. Both THC and chlordiazepoxide decreased fetal weight. There was no indication of synergism between the two drugs for any of the measures examined in this study.