| Study characteristics |
| Methods |
Randomized clinical trial. Open label. One site in Seattle, Washington. Funded by Wyeth |
| Participants |
Age: 18‐45 years old
No COC contraindications
No uterine or cervical abnormalities
No use of contraceptive injection 6 months prior
No intention to become pregnant for 1 year |
| Interventions |
28‐day (21 days with 7‐day hormone free interval; N=40) versus 336‐day (N=39) cycle for 1 year. 100 mcg levonorgestrel and 20 mcg ethinyl estradiol |
| Outcomes |
Bleeding profile, amenorrhea, satisfaction, compliance, endometrial biopsy, endometrial stripe by vaginal ultrasound, weight, blood pressure |
| Notes |
Computer‐generated randomization (blocks of 10). Sequentially numbered sealed brown bags holding study medication. Bleeding defined as spotting needing no protection and bleeding needing protection. Bleeding analysis performed in 84‐day blocks. Satisfaction in Likert format. Power reported. |
| Risk of bias |
| Bias |
Authors' judgement |
Support for judgement |
| Allocation concealment (selection bias) |
Low risk |
A ‐ Adequate |
