Potency of progestogens in oral contraceptives--further delay of menses data.

The original Delay of Menses Test was designed to provide a guide to suitable starting dosages in formulating new contraceptives. The ability of progestogens to maintain uterine hemostasis was measured and a potency relationship among progestogens was predicated. No delay of menses data previously reported have related to tests of progestogens combined with the same dose of estrogen as used in current oral contraceptives. The Delay of Menses Test was repeated using a standardized dose of ethinyl estradiol and doses of four progestogens each found in combination with EE as marketed oral contraceptives. New and more meaningful relative potencies were derived.