Association between body roundness index and infertility in US women: data from National Health and Nutrition Examination Survey (NHANES) 2013–2020

OBJECTIVE: This study aimed to examine the association between body roundness index (BRI) and female infertility. METHOD: This cross-sectional study utilized data from the National Health and Nutrition Examination Survey from 2013 to 2020. BRI was calculated using standardized measurements of height and waist circumference. Multivariable logistic regression models assessed the relationship between BRI and infertility, adjusting for potential confounders. Subgroup analyses examined the stability of the relationship between BRI and infertility, and smooth-fitting curves were applied to explore the linear or non-linear relationship between them. RESULTS: Among the participants, 483 (13.43%) women were diagnosed with infertility. BRI was positively related to infertility (adjusted odds ratio [OR] 1.09; 95% confidence interval [CI] 1.05, 1.13). When categorized into tertiles, women in the highest BRI tertile had a 78% higher risk of infertility (OR 1.78; 95% CI 1.37, 2.32) compared with the lowest tertile. Subgroup analyses revealed potential interactions of age and pregnancy history regarding the association between BRI and infertility, showing an S-shaped relationship in women under 36 years and those without a pregnancy history. CONCLUSION: BRI is positively correlated with infertility in United States women. This finding suggests that BRI could serve as a valuable predictor in female infertility assessment.