Personality beyond the brain: a new perspective on the brain-gut-gonadal axis and human fertility

Despite major advances in reproductive medicine, many cases of infertility remain unexplained. Hormonal, genetic, anatomical, and environmental factors have been extensively investigated, whereas the possible contribution of personality characteristics to reproductive physiology has received little attention. Throughout this review, personality refers to relatively consistent individual characteristics and should not be confused with temporary emotional states or acute psychological stress. Published evidence reports associations between personality characteristics and measures of autonomic and neuroendocrine regulation, gastrointestinal symptoms or function, sexual function, and reproductive health. However, the strength and type of evidence vary across these domains, and most findings are observational or associative rather than causal. Established biological pathways should therefore be distinguished from reported personality-related associations and from the hypothetical cross-system links proposed in this review. This Mini Review examines current evidence linking personality characteristics with autonomic and neuroendocrine regulation, the brain-gut axis, the hypothalamic-pituitary-gonadal axis, sexual function, and fertility. Rather than proposing that internal organs possess personalities, we propose that shared neurobiological and neuroendocrine mechanisms may produce parallel functional response patterns that reflect an individual's personality characteristics. Finally, we propose that integrating these previously studied relationships within a Brain-Gut-Gonadal framework may provide a new perspective on the possible links between personality traits, sexual function, reproductive physiology, and unexplained infertility. This perspective does not imply that personality traits cause infertility, but raises the novel and testable possibility that personality-related biological differences may contribute to individual variation in reproductive physiology and fertility.