Jensen 2012.

Study characteristics
Methods	Randomized clinical trial. Open label. Multicentered trial (84 U.S. sites). Funded by Bayer.
Participants	Age: 18‐45 years old No COC contraindications Regular menstrual cycles No history of infertility Normal pap BMI up to 35 kg/m2
Interventions	Flexible regimen (continuous for at least 24 days, with 4‐day hormone free interval initiated anytime from cycle day 25‐120; N = 234) versus 28‐day cycles (24 days with a 4‐day hormone free interval; N = 232). 3 mg drospirenone and 20 mcg ethinyl estradiol
Outcomes	Bleeding profile, contraceptive efficacy, satisfaction, safety
Notes	Computer‐generated randomization (blocks of 6). Bleeding defined using WHO criteria. Power analysis included. Power analysis included.
Risk of bias
Bias	Authors' judgement	Support for judgement
Allocation concealment (selection bias)	Low risk	A ‐ Adequate