Mechanisms of action of the antifertility agents U11, 100A and U11,555A in the rat.

Mature female rats were given U11,555A and U11,100A on orally on Day 2 of pregnancy and the number of implantations counted on Day 9. Using doses which reduced the implantation number to approximately 40% that of the controls, it was shown that the reduced number was not due to an effect on egg transport or to a delay of implantation.