Contraceptive efficacy, safety, fit, and acceptability of a single-size diaphragm developed with end-user input.

OBJECTIVE:: To estimate contraceptive efficacy safety acceptability and fit of a single-size diaphragm used with contraceptive gel. METHODS:: We conducted a multicenter trial in which 450 couples used the single-size diaphragm 300 randomized to acid-buffering gel and 150 to nonoxynol-9 for at least 190 days and six menstrual cycles. Visits were at enrollment and after menstrual cycles 1 3 and 6. Study outcomes included pregnancy probability safety acceptability and fit. Pregnancy and safety were compared with an historical control group who used a standard diaphragm with these gels. RESULTS:: Most (439/450 [98%]) women could be fitted with the single-size diaphragm. A total of 421 of 450 (94%) provided follow-up. The 35 study pregnancies yielded 6-month Kaplan-Meier cumulative typical use pregnancy probabilities per 100 women with 95% confidence intervals (CIs) of 10.4 (6.9-14.0) for all users and 9.6 (5.5-13.6) and 12.5 (5.4-19.5) with acid-buffering gel and nonoxynol-9 respectively. Historical control analysis yielded a propensity score-adjusted estimate of this pregnancy probability for the single-size diaphragm of 11.3 compared with 10.7 per 100 women for the standard diaphragm ([rounded] difference 0.7 95% CI -3.6 to 4.9). Approximately half (51%) reported at least one urogenital event but compared favorably to the standard diaphragm in historical control analysis. Most (282/342 [82%]) liked the diaphragm. Results suggest that if provided by a clinician 94% (95% CI 92-96%) could insert correctly position and remove the diaphragm. CONCLUSION:: The single-size diaphragm was safe as effective as a standard diaphragm and acceptable when used with contraceptive gel. CLINICAL TRIAL REGISTRATION:: ClinicalTrials.gov www.clinicaltrials.gov NCT00578877. LEVEL OF EVIDENCE:: II.