Intermittent exposure of gravid rats to 1% nitrous oxide and the effect on the postnatal growth of their offspring.

Three groups of pregnant rats were exposed to 1% nitrous oxide 6 hours a day, 5 days per week for the first, first and second, and all 3 weeks of gestation. The offspring were weighed and measured at weekly intervals. The following variables were evaluated in control and experimental groups: litter size, body weight, tail length and body length. Litter sizes in animals exposed for the first and second weeks of gestation were significantly smaller than the controls. A two-way nested statistical analysis of the data revealed that over an 8-week period the experimental rats were significantly smaller than the control rats of the same age. Analysis of the 95% confidence intervals revealed no particular pattern related to the timing of the exposure to nitrous oxide.