Association between Maternal Dietary Patterns and Macrosomia Risk: A Prospective Cohort Study

(1) Background: While dietary interventions offer advantages over conventional medical treatments in some contexts, evidence specifically linking maternal dietary patterns to macrosomia risk remains limited. (2) Method: This prospective cohort investigation enrolled pregnant women residing in Xi'an, China, between December 2023 and February 2024. A validated semi-quantitative food frequency instrument assessed maternal dietary intake. Through factor analysis, predominant dietary patterns were extracted. Neonatal macrosomia was operationally defined as a birth weight of ≥4000 grams, regardless of gestational duration. Poisson regression models were used to estimate risk ratios (RRs) with 95% confidence intervals (CIs) for macrosomia across dietary pattern score quartiles. Stratified analyses and interaction tests were performed for established confounders. (3) Results: Among 1,796 enrolled pregnant women, 1,687 (mean age: 31.0 years) completed the study. Macrosomia was identified in 117 neonates (6.94%). Factor analysis yielded four distinct dietary patterns. Following multivariable adjustment, participants in the highest quartile of the “poultry-offal” and “aquatic-nut” patterns exhibited significantly elevated macrosomia risk-75% and 82% higher, respectively-relative to the lowest quartile (P-trend<0.01). In contrast, Q4 of the “vegetable-fruit” pattern demonstrated a 74% risk reduction versus Q1 (p-trend<0.001). Significant modifying effects of pre-pregnancy BMI and household income were identified for the “staple grain-root” pattern (p-interaction<0.05). (4) Conclusions: High consumption of dark/light green vegetables and fruits conferred marked protection against macrosomia. In contrast, diets rich in poultry, offal, marine fish, freshwater fish, eggs, and nuts were associated with elevated risk. There associations may vary by pre-pregnancy BMI and annual household income. These findings lend epidemiological support to the potential for dietary modifications as a preventive strategy against macrosomia.