Progestational potency of oral contraceptives.

The induction of glycogen deposition as subnuclear vacuoles was found to be a better method in estimating progestational potency of individual progestins than the delay of menses assay. Norgestrel was the most potent progestin in all assays. The progestational potency of oral contraceptives was estimated by multiply potency of individual progestins by their dose. Combination oral contraceptives containing norgestrel were in the mid range of progestational potency because of the relatively higher potency of their progestin. The progestational potency of the norethindrone "mini" pill was compared with that of the norethindrone low-progestogen combination pill and the sequential pill over a 28-day cycle, and no appreciable difference was found.