A multiphasic method of contraception comprising the steps of sequentiallyadministering to a female of child bearing age a Phase I compositioncontaining a progestogen in an amount equivalent to about 0.3 to about 1.5 mgnorethiiidrpne acetate and an estrogen in an amount equivalent to about 5 toaboµt 15 mcg of ethinyl estradiol for about 7 to about 14 days； a Phase IIcomposition containing a progestogen in an amount equivalent to about 0.3 toabout 1.5 mg of norethindrone acetate and an estrogen in an amount equivalentto about 10 to about 25 meg of ethinyl estradiol for about 14 to about 22days； a Phase m composition containing a progestogen in an amount equivalentto about 0.3 to about 1.5 mg of norethindrone acetate and an estrogen in anamount equivalent to about 15 to about 35 meg of ethinyl estradiol for about20 to about 31 days； and an optional Phase IV composition containing (i) anestrogen in an amount equivalent to about 5 to about 20 meg of ethinylestradiol, or (ii) a placebo or a non-steroidal component, or (iii) acombination of (i) and (ii), for about 2 to about 8 days. The ethinylestradiol equivalent amount of estrogen in each of the successive Phases IIand III is at least 5 meg greater than the ethinyl estradiol equivalent amountof estrogen in the immediately-preceding phase.
