The nonlinear association between body roundness index and infertility in married women

Infertility is increasingly linked to obesity, especially visceral fat accumulation. The Body Roundness Index (BRI) provides a precise quantification of body and visceral fat but its implications for infertility risks and diagnostic value are yet to be fully determined. This study analyzed data from 1,305 married women aged 20-45 years, drawn from the National Health and Nutrition Examination Survey (NHANES). Logistic regression was utilized to examine the relationship between BRI and infertility, incorporating univariate and multivariate regression analyses, smooth curve fittings, and subgroup analyses. Additionally, Receiver Operating Characteristic (ROC) analysis assessed the predictive capability of BRI for infertility. An increase in one unit of BRI correlated with a 13% higher prevalence of infertility after adjusting for covariates (OR = 1.13; 95% CI: 1.05, 1.21). Women with higher BRI exhibited greater infertility odds compared to the reference group (OR: 2.20, 95% CI: 1.42, 3.42). Smooth curve fitting analysis revealed a positive, nonlinear relationship, with an inflection point observed at a BRI value of 7.95. Subgroup analyses upheld the robustness of this association across varied demographic segments. ROC curves indicated significant diagnostic potential of BRI in younger women, whereas its predictive relevance diminished in those over 35, akin to other obesity markers. This study is the first to rigorously affirm a strong link between increased BRI and the higher prevalence of infertility among married women aged 20-45. To optimize fertility, maintaining a healthy weight and waist circumference is recommended. The integration of BRI into clinical practice could assist in early intervention for women at risk of infertility. However, further research is required to identify effective predictive markers for infertility in women aged 36-45.