Effects of subanesthetic concentrations of enflurane on rat pregnancy and early development.

Anesthetic pollutants in the operating room have been implicated in producing spontaneous abortion in exposed personnel and congenital malformations among their offspring. To test the effects of trace concentrations of enflurane on pregnancy, rats were exposed to two levels (10.7 and 63.7 ppm) of the anesthetic for 8 hr daily from days 1 to 19 of pregnancy. Litter sizes were not affected but birth weights of exposed offspring were slightly higher than controls. During lactation, cross-fostering studies were performed. Exposed offspring were housed with nonexposed mothers and vice versa to determine if exposure during pregnancy affected early development. Weights at 7, 14, and 21 days of age did not differ among the offspring in the lower dose experiment. Weights of the cross-fostered groups in the high dose experiment were decreased at day seven compared to controls. In the same experiment, exposed offspring housed with exposed mothers were heavier than controls on day 21 of lactation. The modest nature of these alterations suggests that enflurane has little or no gross effect on rat pregnancy and postnatal development.