Objective: To estimate whether continuous combined oral contraceptive pill (OCP) use leads to higher continuation and lower pregnancy rates over 12 months than cyclic use in a developing country setting.
Methods: We enrolled healthy women aged 18 to 30 years, in Santo Domingo, Dominican Republic. We randomly assigned women to cyclic or continuous use of OCPs. Participants made quarterly clinic visits for 12 months. During follow-up, we reviewed OCP adherence and continuation, side effects, and bleeding, and we tested for pregnancy.
Results: We enrolled 358 women (mean age, 22.7 years) and 335 (93.6%) completed the study. In intent-to-treat analyses, 77.6% of the continuous use group and 71.7% of the cyclic group continued OCPs at 12 months (P=.21). The main reason for OCP discontinuation in both groups was running out of OCPs or forgetting. Across all visits, 26.1% of women in the continuous use group and 22.3% of women in the cyclic group ever reported missing three or more OCPs in the past month (P=.43). In multivariable analyses, regimen was not associated with discontinuation, but both previous birth and perceived ease of use of OCPs decreased risk of discontinuation, whereas desire for reduced menstruation increased risk of discontinuation. Although more women reported amenorrhea or infrequent bleeding in the continuous use group, more women in the cyclic group found their bleeding patterns acceptable. Bleeding was not associated with discontinuation in multivariable analyses. Pregnancy rates at 12 months were similar (16.2% continuous and 17.4% cyclic).
Conclusions: Continuous and cyclic OCP regimens were associated with similar 12-month continuation and pregnancy rates. Few factors predicted OCP discontinuation or pregnancy.
Clinical trial registration: ClinicalTrials.gov, www.clinicaltrials.gov, NCT00570440.
Level of evidence: I.