Higher body roundness index (BRI) increases infertility among U.S. women aged 18-45 years.

ObjectiveInfertility is associated with obesity. The Body Roundness Index (BRI) is a body measurement index related to obesity that more accurately assesses body and visceral fat levels. However, the relationship between BRI and infertility remains unclear. Therefore, this study aims to determine the relationship between BRI and infertility.MethodsThis study utilized data from the National Health and Nutrition Examination Survey (NHANES) from 2013 to 2018 and included 3,528 women aged 18-45 years. Multivariate logistic regression was employed to investigate the association between BRI and infertility. Restricted cubic spline (RCS) analysis explored the linear or non-linear relationship between BRI and infertility. Interaction analyses were conducted on subgroups to validate the findings. To verify the robustness of the results, we performed several sensitivity analyses, including propensity score matching(PSM) and multiple imputations for missing data. Furthermore, the predictive capabilities of various anthropometric indices-including BRI, weight-adjusted waist index (WWI), body mass index (BMI), and weight-on infertility incidence were assessed using Receiver Operating Characteristic (ROC) curve analysis.ResultsThere was a significant positive association between BRI and infertility. After adjusting for covariates, for each unit increase in BRI, there was a 12% increase in the probability of infertility (P < 0.001). This positive correlation persisted when BRI was categorized into quartiles. Moreover, as BRI increased, there was a trend towards higher infertility prevalence (P for trend < 0.001). The dose-response curve indicated a linear association between BRI and infertility, with higher BRI associated with higher infertility risk. The correlation between BRI and infertility persisted in subgroup analysis and multiple imputations. The ROC curve analysis revealed that BRI had a superior predictive capability compared to traditional obesity indices, with an area under the curve (AUC) of 0.618 (95% CI, 0.588-0.648).ConclusionThe results of this study show a strong positive correlation between BRI and the prevalence of infertility.Clinical trial numberNot Applicable.