Cross-sectional association between adherence to a planetary health diet and self-reported infertility in U.S. women (NHANES 2013-2018)

Abstract

The relationship between dietary patterns aligned with the EAT-Lancet reference diet, which promotes both human and planetary health, and female infertility remains unexplored. This study aimed to investigate the association between adherence to the plant-based diet index (PHDI) and infertility among United States women of reproductive age. We conducted a cross-sectional analysis of data from the 2013 to 2018 National Health and Nutrition Examination Survey. The study included 3105 women aged 20 to 45 years. The PHDI (0-150 points) was calculated from 2 nonconsecutive 24-hour dietary recalls, with higher scores indicating greater adherence. Infertility was defined as self-reported attempts to conceive for ≥1 year without success. Multivariable logistic regression was used to estimate odds ratios (ORs) and 95% confidence intervals (CIs) for infertility across PHDI levels, adjusting for key demographic, anthropometric, and lifestyle confounders. The mean age of participants was 32.7 ± 7.5 years. Mean PHDI was 43.0 ± 14.3. Overall, 402 women (12.95%) reported infertility. Higher PHDI was associated with lower odds of infertility. In tertile analyses, women in the highest PHDI tertile had a 25% lower likelihood of infertility compared to those in the lowest tertile (adjusted OR = 0.75, 95% CI 0.56-0.99; P = .0469). A trend toward decreasing infertility risk was observed across increasing PHDI tertiles (P for trend = .0486). Treating PHDI as a continuous variable, each one-standard deviation increase in PHDI (~14.3 points) was associated with a 12% reduction in the odds of infertility (OR = 0.88, 95% CI 0.79-0.99; P = .0254). These associations persisted after adjustment for age, ethnicity, poverty income ratio, marital status, smoking status, alcohol use, body mass index, secondhand smoke exposure, hypertension, and total physical activity (MET/week). Sensitivity analyses, including models incorporating survey sample weights, and stratified analyses by age and body mass index, yielded consistent results. Greater adherence to the planetary health diet (higher PHDI) was associated with lower odds of self-reported infertility in this nationally representative sample of United States women. Given the cross-sectional design, causality cannot be established; however, the results underscore diet quality as a potentially important factor in self-reported infertility.

Keywords: NHANES; Planetary Health Diet Index; diet quality; epidemiology; female fertility; infertility; nutrition; reproductive health; sustainable diet.