| Methods |
11 sites in the USA
Four treatment cycles.
Unblinded. |
| Participants |
Healthy women at risk for pregnancy with regular menses.
Excluded contraindications for oral contraceptive use; smokers aged 35 years or older; heavy smoking; recent oral injectable, implantable, or intrauterine contraceptive use; and drug or alcohol abuse. |
| Interventions |
EE 20 µg and levonorgestrel 100 µg (N=169) versus EE 35 µg and norethindrone 500‐750‐1000 µg (N=173). |
| Outcomes |
Cycle control.
'Withdrawal' bleeding or spotting defined as bleeding or spotting beginning in pill‐free interval and stopping by fourth day of the next cycle. 'Intermenstrual' bleeding defined as all other bleeding. |
| Notes |
Randomization method not reported.
Excluded randomized women from the analysis.
56% (191/342) completed study. |
| Risk of bias |
| Bias |
Authors' judgement |
Support for judgement |
| Allocation concealment (selection bias) |
Unclear risk |
Not reported |
