Effects of prenatal exposure to cigarette smoke and nicotine on pregnancy, offspring development and avoidance behavior in rats.

Pregnant rats were exposed to cigarette smoke or injected with nicotine twice daily on days 1 to 20 of gestation. In the smoke-exposed rats, weight gain during pregnancy was significantly reduced. On the other hand no significant effect was observed on delivery rate, litter size, weight of offspring, percent weight of the brain, number of dead fetuses, offspring mortality during lactation and ratio of males to females. No gross malformation was detected. The offspring were trained for avoidance conditioning when 60 days old: the number of rats satisfying the criterion of learning at the end of conditioning was quite similar in the three groups, but the rate of avoidance acquisition was significantly greater in the offspring of the dams exposed to cigarette smoke.