Relationship of weight-adjusted waist index and body mass index with infertility: A NHANES 2015 to 2018 cross-sectional study

Obesity is a significant risk factor for female infertility, representing a growing global health concern. Body mass index (BMI) has traditionally been used as the standard measure of obesity; however, the weight-adjusted waist index (WWI) has recently appeared as a novel metric that may provide a more accurate assessment of obesity. This study aims to investigate the association of both BMI and WWI with female infertility. The “2015–2018 National Health and Nutrition Examination Survey” (NHANES) was utilized to derive the data. The study included 2393 women between the ages of 20 and 50 years. Among them, 251 were diagnosed with infertility. Multivariate logistic regression, subgroup analysis, interaction testing, smooth curve fitting, and receiver operating characteristic curve analysis were conducted to examine the associations of WWI and BMI with infertility. Among women, the infertility’s prevalence was positively associated with both WWI and BMI levels. Higher WWI was significantly related with raised infertility prevalence (OR = 3.63, 95% CI: 1.96–6.73), as was higher BMI (OR = 2.27, 95% CI: 1.29–4.01). In the WWI subgroup analysis, the association was consistently observed in most subgroups, except for age, race, and education level. In the BMI subgroup analysis, the association was consistent across all subgroups. In the population-based cross-sectional data of this study, WWI and BMI were positively associated with the odds of infertility among US women. This finding suggests that obesity-related measures may have potential value in clinical practice and may help to identify potentially high-risk groups of women with infertility. In addition, the existing results suggest that weight management-related interventions may have potential effects on fertility outcomes, but whether they can reduce the infertility rate, explain the biological mechanism, and guide clinical decision-making needs to be verified by prospective, mechanistic, and interventional trials in the future.