Assessment of the dietary and nutritional status of Iranian pregnant women: a study employing both a priori and a posteriori analytical approaches

Dietary pattern analysis provides a holistic assessment of diet quality critical for maternal-fetal health, offering insights superior to single-nutrient evaluation. Hereby, we aimed to concurrently evaluate established a priori and data-driven a posteriori dietary patterns, alongside nutrient-mineral adequacy, among pregnant women. This cross-sectional study recruited 233 women in their first trimester from "Mazandaran, Iran" province between 2020 and 2023. Dietary intake was measured via a validated 168-item Food Frequency Questionnaire. Adherence to predefined guidelines was assessed using a modified 8-point Mediterranean Diet Score (MDS) and three Nutrient Rich Food (NRF) indices (NRF6.3, NRF9.3, NRF15.3). Empirical patterns were derived using Principal Component Analysis (PCA) on 26 food groups via R Studio. Nutritional status was quantified using the Mean Adequacy Ratio (MAR), Protein Adequacy Ratio (PAR), and adequacy metrics for other nutrients/minerals. The study exhibited high metabolic risk factors in pregnant women, with 61.0% overweight/obese and 59.2% vitamin D deficient. Overall diet quality was suboptimal, evidenced by low MDS (Mean = 3.35) and poor micronutrient density (Mean MAR = 0.624), signifying that diets met only approximately 62% of recommended intakes. PCA identified a healthy "Prudent" pattern (PA2), a mixed "Traditional" pattern (PA1), and an unhealthy "Western" pattern (PA3). Increased adherence to the Prudent pattern significantly correlated with improved MAR, PAR, and a desirable decrease in Na/K ratio. Conversely, adherence to the Beverage & Fast-food pattern was associated with pervasive declines in all adequacy markers, including a severely decreased MDS (β = -0.26, p-value = < 0.001). Pregnant women in this regional study exhibit critically suboptimal dietary quality and significant micronutrient shortfalls, largely driven by low adherence to prudent, nutrient-dense patterns, and the majority depend on unhealthy food choices.