Association between dietary quality indices and female infertility: a population-based study using NHANES 2013–2020

This study investigated the association between dietary quality indices and female infertility using data from the National Health and Nutrition Examination Survey (NHANES) 2013–2020. A total of 5,477 women aged 18–59 years were included. Dietary quality was assessed using 24-hour dietary recall data and summarised by four predefined indices: the alternate Mediterranean diet score (MED), the Healthy Eating Index–2020 (HEI-2020), the Alternate Healthy Eating Index (AHEI), and the Dietary Approaches to Stop Hypertension (DASH) score. Weighted logistic regression models were used to estimate the associations between dietary quality and infertility, and restricted cubic spline (RCS) analyses were used to examine potential dose–response patterns. After adjustment for age, race/ethnicity, education level, body mass index (BMI), smoking status, alcohol consumption, marital status, menstrual regularity, age at menarche, history of pelvic inflammatory disease, and total energy intake, higher MED, HEI-2020, AHEI, and DASH scores were inversely associated with infertility. RCS analyses suggested approximately linear inverse associations for these indices (all P for nonlinearity >0.05). Higher overall diet quality was associated with lower odds of infertility among adult women in the United States (US). Because this was a cross-sectional study using self-reported infertility, the findings should be interpreted as associative rather than causal.