Caffeine induces cardiac and other malformations in the rat.

At various gestational periods, caffeine was injected intra-arterially or intraperitoneally into pregnant rats. The teratogenic effects of caffeine on the fetal heart were dose dependent and detectable at relatively low concentrations. The most susceptible stage was during septation of the heart. The most common cardiovascular malformation was ventricular septal defect. Extracardiovascular anomalies, such as decreased thymic weight and degeneration of the lens, were found in all fetuses; skeletal malformations were found in some fetuses.