The Impact of Dietary Nutrient Intake on Red Blood Cell Distribution Width-Coefficient of Variation in Pregnant Women: A Cross-Sectional Observational Pilot Study

Background/Objectives: Dietary intake during pregnancy influences hematological parameters, reflecting nutritional status and potentially affecting maternal and fetal outcomes. This cross-sectional pilot study aimed to compare dietary nutrient intake in pregnant women depending on their red cell distribution width-coefficient of variation (RDW-CV). Methods: A total of 31 pregnant women in their third trimester were divided into the following two groups: within reference range RDW-CV (n = 22) and elevated RDW-CV (n = 9). Dietary intake was assessed via a dietary recall (USDA Multiple-Pass Method). Intake of energy (kcal/day), macronutrients (g/day), vitamins (mg/day; µg/day) B1, B3, B6, B9, B12, C, A, D, E, and minerals (mg/day) Zn, P, Mg, K, Ca, Fe were recorded. Complete blood count (CBC) parameters were measured (Total WBC, HGB, HCT, MCV, RDW-CV, PLT, NEU, LYM, MON, EOS, BAS, LMR). Results: The elevated RDW-CV group had a significantly lower level of daily energy adequacy. Both groups did not meet recommended intakes for energy, iron, vitamin D. A statistical significance in MCV differences was noted, with lower values in the elevated RDW-CV group, supported by a Cohen’s d = 0.82, suggesting early changes in erythrocyte size distribution. The reference range RDW-CV group consumed significantly more zinc, phosphorus, calcium, and vitamin B12, whereas vitamin C intake was higher in the elevated RDW-CV group. Conclusions: Pregnant women with an elevated RDW-CV tended to exhibit greater nutritional insufficiencies than those with reference range RDW-CV. Our findings suggest potential associations between hematologic indices (RDW-CV, MCV) and dietary nutrient intake patterns during pregnancy. These preliminary observations are based on a pilot study and warrant confirmation in larger, prospective studies incorporating biochemical markers.