Associations of Dietary Index for Gut Microbiota and Flavonoid Intake With Female Infertility in the United States.

This study aimed to investigate the associations between a dietary index for gut microbiota (DI-GM), flavonoid intake, and female infertility, while exploring age-specific differences in these relationships to identify potential dietary strategies for female infertility prevention. This cross-sectional study focused on female participants aged 18-45 years, with data obtained from the 2017-2018 cycle of the National Health and Nutrition Examination Survey (NHANES). Weighted multivariable logistic regression models were employed to examine the associations between DI-GM, flavonoid intake, and self-reported female infertility. Age-stratified analyses were performed to evaluate whether these associations varied across reproductive life stages. Higher DI-GM scores were significantly associated with reduced infertility risk (aOR = 0.30, 95% CI: 0.13-0.71,  = 0.006), with the strongest protective effects observed in women aged < 35 years (Q3: aOR = 0.13, 95% CI: 0.03-0.58,  = 0.007; Q4: aOR = 0.27, 95% CI: 0.09-0.77,  = 0.015). Beneficial gut microbiota scores also showed a protective effect (aOR = 0.75, 95% CI: 0.57-0.98,  = 0.036). Among women aged ≥ 35 years, moderate flavonoid intake (Q2) showed a significant inverse association with female infertility risk (aOR = 0.19, 95% CI: 0.06-0.66,  = 0.009). Our findings reveal novel evidence that higher DI-GM scores and moderate flavonoid intake are significantly linked to a lower risk of female infertility, with age-specific patterns observed. Higher DI-GM scores showed significant protective effects in younger women (< 35 years), while moderate flavonoid intake was protective in women aged ≥ 35 years. These findings underscore the potential of personalized dietary strategies targeting gut microbiota composition and flavonoid intake as cost-effective approaches for female infertility prevention and management across different reproductive life stages.