Positive treatment effects and high heterogeneity of hormonal contraceptive use on women's sexuality

Different women experience hormonal contraceptives differently, reporting side effects on their sexuality that range from negative to positive. But research on such causal effects of hormonal contraceptives on psychological outcomes struggles both to identify average causal effects and capture the high heterogeneity in women’s treatment responses. In this study, we leveraged longitudinal data to improve our ability to separate the causal effects of hormonal contraceptives from other sources of association, including observed and unobserved confounding, reverse causality, and attrition. In this programmatic registered report (programmatic registered stage 1 protocol: https://osf.io/kj3h2; date of in-principle acceptance: 28/09/2023), we analyzed data from up to 5,041 women (23,130 observations), who participated in PAIRFAM, a German longitudinal panel dataset consisting of 14 waves, using Bayesian multilevel regressions. To deal with confounding and probe the robustness of findings, we implemented two analysis approaches: adjusted regression analysis and inverse probability of treatment weighting approach. We found evidence for positive average treatment effects of hormonal contraceptives on sexual frequency and sexual satisfaction, but no robust evidence for effects on desired sexual frequency. Furthermore, to move beyond average treatment effects, we analyzed heterogeneity in treatment responses. We found relatively high heterogeneity in individual treatment effects on sexual frequency and sexual satisfaction. Interindividual differences were not systematically related to individual treatment effects, and those treatment effects did not predict women’s decisions about which contraceptive method to use in the long run. Our results contribute to understanding the effects of hormonal contraceptives on sexuality in a naturalistic setting, where women adapt their choice of contraceptive method to their own experiences.