Comparison of short-term efficacy, side effects, benefits of two drospirenone containing combined oral contraceptives: 21/7-day-3mg/30mcg vs. 24/4-day-3mg/20 mcg

To compare two lower dose drospirenone/ethynilestradiol (EE) combination oral contraceptives (COC) (21/7 3mg/30mcg vs 24/4 3mg/20mcg) in terms of short-term effects on ovulation, efficacy, side effects and benefits.