Non-linear association between body roundness index and menopausal symptoms in perimenopausal and postmenopausal women

Objective This study aimed to examine the association between body roundness index (BRI) and menopausal symptoms in Chinese perimenopausal and postmenopausal women.Method The cross-sectional study enrolled 1795 perimenopausal and postmenopausal women aged 40–69 years who attended the Menopause Clinic at Guangdong Women and Children Hospital. Menopausal symptom severity was assessed using the validated Chinese-modified Kupperman Menopause Index (KMI). Multivariable logistic regression and restricted cubic splines were used to estimate odds ratios (ORs) and identify potential thresholds.Results Overall, 78.8% of participants reported menopausal symptoms, most of which were mild to moderate. Higher BRI was independently associated with higher odds of menopausal symptoms after adjustment for covariates in a multivariable logistic regression model (OR: 1.20, 95% confidence interval [CI]: 1.05–1.38, p = 0.009). Restricted cubic spline analysis revealed a non-linear relationship between BRI and menopausal symptoms (p-value for non-linearity = 0.014), with a data-derived inflection point at 2.571. Among women with BRI exceeding 2.571, the odds of menopausal symptoms increased progressively with rising BRI (OR: 1.34, 95% CI: 1.11–1.62, p = 0.002). Subgroup analyses showed consistent associations across strata (all p-values for interaction > 0.05).Conclusion The BRI may serve as a useful anthropometric marker for identifying midlife women with greater symptom burden, although causal inference requires prospective validation.