Metabolism Study to Investigate the Impact of a Sequential Oral Contraceptive

7 treatment cycles of 28 days each (no tablet-free intervals); Days 1-2: 3.0 mg EV; Days 3-7: 2.0 mg EV + 2.0 mg DNG; Days 8-24: 2.0 mg EV + 3.0 mg DNG; Days 25-26: 1.0 mg EV; Days 27 - 28: Placebo

7 treatment cycles of 28 days each (no tablet-free intervals);Days 1-6: 0.03 mg EE + 0.05 mg LNG; Days 7-11: 0.04 mg EE + 0.075 mg LNG; Days 12-21: 0.03 mg EE + 0.125 mg LNG;Days 22-28: Placebo