Hormonal Contraceptives and the Gut Microbiome in Female Athletes: Implications for Health, Performance, and Exercise-Related Physiological Adjustments.

Hormonal contraceptives are widely used among female athletes, with documented prevalence rates varying from 29% to 65% across different sports disciplines. Growing evidence suggests that hormonal contraceptives may influence the diversity and composition of the gut microbiome. A particular concern is a potential reduction in beneficial bacteria responsible for producing short-chain fatty acids, which could impact both overall health and the body's adaptation to exercise training. This narrative review examines the current understanding of the links between hormonal contraceptive use, changes in gut bacteria, and exercise-related physiological adaptations in female athletes. A comprehensive literature search of PubMed and Google Scholar (2017-2025) was conducted using terms related to hormonal contraception, gut microbiota, and exercise. Due to the scarcity of studies directly investigating all three factors together, the search also included research on the relationships between each pair of these elements. Eighty-eight relevant articles were identified and included. While regular physical activity is generally known to support a healthy and diverse gut microbiome, hormonal contraception might counteract these positive effects. Hormonal contraceptives appear capable of disrupting the community of gut microbes involved in regulating estrogen, potentially reducing overall microbial diversity and promoting harmful imbalances. Critically, within the scope of this review, only one pilot study has been identified as directly exploring these interactions in female athletes. This key study found that athletes using hormonal contraceptives showed a decrease in the types of gut bacteria that produce beneficial short-chain fatty acids. Proposed pathways through which contraceptive-induced microbial changes might affect exercise adaptation and performance include alterations in energy metabolism, impaired immune function, weakening of the gut barrier, and disruption of natural hormonal balance. The impact likely depends on the specific type of contraceptive used, with combined oral contraceptives potentially having stronger effects than progestin-only methods. Given the current limited evidence, particularly the lack of direct studies beyond the pilot study mentioned, it is premature to draw definitive causal conclusions. However, the potential interactions suggest important practical implications. These include developing individualized approaches to training programming, nutritional strategies (such as optimizing fiber and prebiotic intake to support beneficial microbes), and contraceptive counseling for female athletes (e.g., involving physicians, sports dietitians, and coaches). Future research must prioritize well-designed studies, including randomized controlled trials and long-term observations, specifically in athletic populations. Such research is essential to develop evidence-based guidelines that can help optimize both the health and performance of female athletes who use hormonal contraception. To our knowledge, this review is the first to synthesize the complex relationship between contraceptive use, gut bacteria, and exercise adaptation specifically within female athletic cohorts.