Hormonal contraceptive use and women’s sexuality and well-being: Estimating treatment effects and their heterogeneity based on longitudinal data [Stage 1 registered report]

Different women experience hormonal contraceptives differently, reporting side effects on their sexuality and well-being 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 plan to leverage 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. We will analyze data from up to 6,565 women who participated in PAIRFAM, a German longitudinal panel dataset consisting of 13 waves using Bayesian multilevel regressions. To deal with confounding and probe the robustness of findings, we will implement two analysis approaches: adjusted regression analyses and inverse probability of treatment weighting analyses. Furthermore, to move beyond average treatment effects, we will analyze heterogeneity in treatment responses and test whether interindividual differences can predict such heterogeneity. Lastly, we will investigate whether treatment response predicts women’s decisions about which contraceptive method to use in the long run. Our results will help to understand the impact of hormonal contraception on sexuality and well-being in a naturalistic setting in which women adapt their contraception to their own experiences.