A method for contraception includes administering to a female daily, in a fourphasic dosing regimen during a time period of 24 successive days, an oral combination drug formulation of norethindrone acetate and ethinyl estradiol (EE), wherein doses in the second, third and fourth phases of the regimen increase by a predefined dose increment as compared to the corresponding doses administered during the previous phase, wherein the norethindrone acetate dose in the first phase is 1000 mcg, in the second phase is 1125 mcg, in the third phase is 1250 mcg, and in the fourth phase is 1375 mcg, wherein the EE dose in the first phase is 20 mcg, in the second phase is 22.5 mcg, in the third phase is 25 mcg, and in the fourth phase is 27.5 mcg, and wherein the fourphasic dosing regimen is followed by 4 days without norethindrone acetate and EE administration.