Studies on the embryotoxic risk of exposure to caffeine and ethanol during the preimplantation period in the mouse.

Pregnant mice were exposed before implantation to caffeine and ethanol to determine the dose-response relation for embryolethality during the preimplantation period. For risk estimation the embryotoxicity was evaluated at term and also 24 h after implantation. For ethanol no embryotoxic risk could be detected. Caffeine unexpectedly exhibited a high risk for embryoethality when compared to the maternal LD50. However, when taking into account realistic exposure levels an embryotoxic risk in early pregnancy can be excluded in humans for both caffeine and ethanol.