Assessment of incremental dosage regimen of combined oestrogen-progestogen oral contraceptive.

Eighty-six women of proved fertility used an incremental dosage regimen of a combined oral contraceptive for a total of 570 cycles over one year. A daily tablet containing 50 mug of ethinyloestradiol and 50 mug D-norgestrel was taken for 11 days and a daily tablet containing 50 mug ethinyloestradiol and 125 mug D-norgestrel for the next 10 days. Withdrawal bleeding occurred during the tabletfree interval of seven days. The new preparation proved to be an efficient contraceptive, well tolerated, and with few side effects. Women who had gained weight while taking other oral contraceptives lost weight when they changed to the new preparation. The regimen allowed a significant reduction in the cycle dose of progestogen, and these results suggest that a further reduction in the cycle dose of both oestrogen and progestogen may be possible without losing contraceptive efficiency.