Effects of a preovulatory single low dose of mifepristone on ovarian function.

Objectives: To investigate the effect of a single low dose of mifepristone on ovarian function, when administered in the preovulatory period.

Methods: Healthy women with regular menstrual cycles were studied during two consecutive menstrual cycles. Either mifepristone or placebo was given in a randomized double-blind order when the leading follicle reached a diameter between 15 and 17 mm.