Does the Composition of Breast Milk in the First Week Postpartum Differ Due to Maternal Factors or Neonatal Birth Weight and Percent Fat Body Mass?

Background: The composition of breast milk is dependent on numerous factors. However, the precise impact of maternal health conditions on breast milk composition remains to be fully elucidated. Similarly, there is a paucity of evidence regarding the correlation between neonatal body composition and human milk. The objective of the study was to evaluate the macronutrient composition of breast milk collected during the first week postpartum from mothers with gestational diabetes and healthy mothers in terms of selected maternal and neonatal factors. Methods: n = 70 breast milk samples were analyzed for fat, protein, carbohydrate, dry matter, true protein, and energy. The results were evaluated in terms of selected maternal factors, as well as neonatal birth weight (BW) and percent fat body mass (%FBM), which was assessed with a bioimpedance method. Results: Energy of breast milk in the study group was as follows: median 55.5 kcal/dL in GDM G1, median 55.5 kcal/dL in GDM G2, and median 65.0 kcal/dL in non-GDM, which differed significantly in Kruskal-Wallis ANOVA. Neonatal %FBM, but not BW, was found to be significantly related to concentrations of protein, true protein and dry matter. Maternal gestational weight gain, history of hypothyroidism, and classification by study group were identified as factors affecting both breast milk and neonatal body composition. Conclusions: The composition of breast milk in the initial week following childbirth is predominantly determined by maternal factors. The relationship between selected macronutrients and neonatal percent fat body mass was found to be weak, yet the significance of this finding is unclear. Further research is required to ascertain the influence of maternal milk composition on early infantile nutritional programming.