Contraceptive adherence and frequency of sex among oral contraceptive users: Findings from the Contraceptive History, Initiation, and Choice Study

Purpose Among oral contraceptive (OC) users, adherence to the dosage regimen and frequency of sex are major determinants of unintended pregnancy. Though integral to studies of fertility and contraceptive effectiveness, information on these determinants is limited. The purpose of the Contraceptive History, Initiation, and Choice (CHIC) Study is to determine factors related to adherence and frequency of sex. Methods Women between the ages of 18–45 who were using birth control were approached while waiting for appointments at a family medicine clinic in Atlanta. Those who agreed signed an informed consent form and filled out a short baseline survey. Current OC users were invited to participate in a longitudinal study. Of 158 identified OC users, 98 returned 413 weekly diaries containing daily information on adherence and frequency of sex. Logistic regression for correlated responses was used to obtain odds ratios (ORs) and 95% confidence intervals (CIs). Results Women using OCs to regulate their menstrual cycles had increased odds of adherence (OR = 2.74, 95% CI: 1.07, 7.02). Black women had decreased odds of having sex (OR = 0.47, 95% CI: 0.23, 0.96), as did women experiencing menstrual bleeding (OR = 0.56, 95% CI: 0.41, 0.78). With regards to adherence, there was no association between missing ≥1 pill during a week and sex (OR = 0.94, 95% CI: 0.53, 1.64). However, women who deviated from their self-reported pill taking time by ≥2 hours had increased odds of having sex (OR = 1.60, 95% CI: 1.13, 2.29). Conclusion A diverse group of well-educated, sexually active OC users frequently forgot to take pills or did not take them at a consistent time, thereby increasing their risk of unintended pregnancy. Subgroup analyses of this exploratory study suggest associations that should be further investigated with respect to their impact on fertility, contraceptive effectiveness, and sexually transmitted infections