Oelkers 2000.

Methods	Study 2: Three centers in The Netherlands and Belgium. One pill‐free pre‐treatment cycle and three treatment cycles. Study 3: One site in The Netherlands. Two pill‐free pretreatment cycles, 13 treatment cycles and one follow up cycle.
Participants	Study 2 and 3: Women age 18 to 35 years (18 to 30 years for smokers) with regular menses. Excluded pregnancy.
Interventions	Study 2: Drospirenone 2 mg and EE 30 µg (N=35) versus drospirenone 3 mg and EE 30 µg (N=35). Study 3: Drospirenone 3 mg and EE 30 µg (N=30) versus desogestrel 150 µg and EE 30 µg (N=30).
Outcomes	Study 2 and 3: Renin‐angiotensin‐aldosterone system, body weight.
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	No information
Allocation concealment (selection bias)	Unclear risk	No information
Blinding (performance bias and detection bias) All outcomes	Unclear risk	Study 2, no information; study 3, unblinded.
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Early discontinuation and loss to follow up not reported.