Anesthetics as teratogens: nitrous oxide is fetotoxic, xenon is not.

Exposure of pregnant rats to the anesthetic nitrous oxide on the ninth day of gestation causes fetal resorption, skeletal anomalies, and macroscopic lesions including encephalocele, anophthalmia, microphthalmia, and gastroschisis. The inert gas xenon, which has anesthetic properties similar to those of nitrous oxide, does not cause teratogenic effects under the same experimental conditions.