Effects of the anti-progestin RU 38486 on rat embryos growing in culture.

RU 38486 is a steroid currently manufactured as an abortifacient. In view of the lack of conclusive information about teratogenic risk, it is current practice for most human embryos surviving RU 38486 to be surgically aborted. In this study the effects were examined of different concentrations of RU 38486 on postimplantation rat embryos in culture. No statistically significant effects were observed until the doses reached x 7 the 'standard' dose (x 1). The experiments provide no evidence of a teratogenic effect of RU 38486 at the levels currently used in clinical practice.