A multiphasic method of contraception comprising the steps of sequentially administering to a female of child bearing age a Phase I composition containing a progestogen in an amount equivalent to about 0.3 to about 1.5 mg norethindrone acetate and an estrogen in an amount equivalent to about 5 to about 15 mcg of ethinyl estradiol for about 7 to about 14 days； a Phase II composition containing a progestogen in an amount equivalent to about 0.3 to about 1.5 mg of norethindrone acetate and an estrogen in an amount equivalent to about 10 to about 25 mcg of ethinyl estradiol for about 14 to about 22 days； a Phase III composition containing a progestogen in an amount equivalent to about 0.3 to about 1.5 mg of norethindrone acetate and an estrogen in an amount equivalent to about 15 to about 35 mcg of ethinyl estradiol for about 20 to about 31 days； and an optional Phase IV composition containing (i) an estrogen in an amount equivalent to about 5 to about 20 mcg of ethinyl estradiol, or (ii) a placebo or a non-steroidal component, or (iii) a combination of (i) and (ii), for about 2 to about 8 days. The ethinyl estradiol equivalent amount of estrogen in each of the successive Phases II and III is at least 5 mcg greater than the ethinyl estradiol equivalent amount of estrogen in the immediately-preceding phase.
