Effects of marihuana on pregnant rats and their offspring.

Pregnant rats were intubated with marihuana extract (10, 150 mg/kg) from gestation day 3 to parturition. Control animals were pair-fed. At parturition pups were culled and assigned to nondrug-treated dams. A positive control group consisting of animals prenatally exposed to alcohol (6 g/kg/day) was included for comparison of birth weight data. Marihuana reduced food and water consumption and maternal weight gain. Pup weight at birth was reduced by about 10% relative to pair-fed controls in animals exposed to the high doses of marihuana, and by approximately 15% in pups exposed to alcohol relative to their pair-fed controls. Litter size and pup mortality at birth were not affected significantly. Postnatal mortality was increased and neonatal weight was decreased at 21 days in marihuana-treated offspring. At 11 weeks of age body weights of drug-treated females but not males, were still significantly less than that of pair-fed controls.