Associations Between Total and Regional Fat-to-Muscle Mass Ratio with the Prevalence of Infertility: A Cross-Sectional Study.

Purpose: The fat-to-muscle mass ratio (FMR) is a novel anthropometric parameter that integrates the antagonistic effects of fat and muscle mass. The current study aimed to examine the associations between total and region-specific FMR with the prevalence of self-reported infertility in US women. Methods: US women aged 20 to 44 years from the 2013-2018 National Health and Nutrition Examination Survey were included. Total, trunk, arm, and leg FMR were calculated from fat mass and muscle mass in the corresponding body part by dual-energy X-ray absorptiometry. Binary logistic regression, restricted cubic spline analysis and subgroup analysis were primarily used for statistical analyses. Results: Infertility prevalence was 12.77% among the 1958 women included. Arm and leg FMR were not associated with infertility prevalence, while the odds ratio and 95% confidence intervals for infertility by each 0.1 point increase in trunk and total FMR were 1.19 (1.07-1.33) and 1.16 (1.04-1.30), respectively. Restricted cubic spline analysis indicated a positive and linear relationship between trunk or total FMR and infertility prevalence. Subgroup analysis consistently demonstrated that the associations between trunk or total FMR with infertility prevalence were more pronounced in women without a pregnancy history than in those with a pregnancy history. The receiver-operating characteristic curves indicated that the trunk FMR outperformed total, arm, and leg FMR in discriminating infertility from women without infertility. Conclusion: Trunk and total FMR, rather than arm or leg FMR, were associated with an increased risk of infertility in US women, especially those without a prior pregnancy history.