| Methods |
11 sites in the USA
Four treatment cycles.
Unblinded. |
| Participants |
Healthy women over aged 18 years at risk for pregnancy with regular menses.
Excluded smokers over age 35 years; contraindications for oral contraceptive use; and recent oral contraceptive, intrauterine device, injectable, or implantable estrogens, progestins, or androgens. |
| Interventions |
EE 20 µg and levonorgestrel 100 µg (N=192) versus EE 35 µg and norethindrone 500‐750‐1000 µg (N=195). |
| Outcomes |
Cycle control and safety.
'Withdrawal' bleeding or spotting was defined as bleeding or spotting beginning in pill‐free interval and stopping by fourth day of the next cycle. 'Intermenstrual' bleeding was defined as all other bleeding. |
| Notes |
Excluded randomized women from the analysis.
57% (220/387) completed study. |
| Risk of bias |
| Bias |
Authors' judgement |
Support for judgement |
| Allocation concealment (selection bias) |
Low risk |
Allocated with sequentially numbered, sealed envelopes. |
