Cycle Control Assessment of a Combined Oral Contraceptive Containing Estetrol and a Progestin P1 or P2

"6 treatment cycles each consisting of 28 days of oral administration as follows:~* Days 1-24: one estetrol tablet and one P1 tablet per day~* Days 25-28: two placebo tablets per day"

"6 treatment cycles each consisting of 28 days of oral administration as follows:~* Days 1-24: one estetrol tablet and one P2 tablet per day~* Days 25-28: two placebo tablets per day"

"6 treatment cycles each consisting of 28 days of oral administration as follows:~* Days 1-26: one tablet of Estradiol valerate/dienogest per day~* Days 26-28: one placebo tablet per day"