Ultra-processed food intake and Mediterranean diet adherence in relation to fertility status in U.S. women: Findings from NHANES 2013–2018

Abstract

Background: Dietary quality is a critical determinant of reproductive health, yet little is known about how distinct dietary patterns and food processing affect fertility outcomes in the general population. Aim: To examine the associations between ultra-processed food (UPF) intake and Mediterranean diet (MD) adherence and self-reported fertility among American women of reproductive age. Methods: We analyzed data from 2582 women aged 20–45 years participating in the 2013–2018 National Health and Nutrition Examination Survey. Fertility status was defined based on self-reported attempts to conceive for ≥12 months. Dietary data collected by two 24-h dietary recalls was used to classify UPFs according to the Nova classification and UPF intake was defined as % grams per day. MD adherence was assessed using a modified 8-point score. Multivariable logistic regression models were used to examine associations, adjusting for sociodemographic and health covariates, including obesity. Summary: The mean UPF intake was 27.15% of daily intake (g/day) and the mean MD score was 3.35 out of 8. Women reporting infertility had significantly higher UPF intake and lower MD scores compared to fertile women. Higher UPF intake was significantly associated with lower odds of fertility in the fully adjusted model (OR = 0.32; 95% CI: 0.14, 0.75). MD adherence was initially associated with higher odds of fertility (OR = 1.16; 95% CI: 1.00, 1.33), though this association was no longer significant when adjusted for obesity. These findings underscore the need for dietary guidance targeting women of reproductive age.