A human milk perspective on the transmission of maternal factors to her child Focus on stress, nutrition and immunity

The early postpartum period is a critical time window of development during which maternal influences can lastingly affect the infant’s development and health through complex, multi-dynamic, and not yet completely understood mechanisms. In this thesis, we explore the hypothesis that human milk (HM) is one of these mechanisms by investigating three potential maternal impacts on HM composition, their interplay and their potential consequences for the infant, namely; maternal stress, nutrition and immunity.In this thesis we demonstrated that maternal stress was associated with a different HM fatty acid, amino acid, oligosaccharide and microbiome composition. In addition, we demonstrated that postpartum stress was associated with dietary intake in lactating women, which may in turn affect the composition of HM. Moreover, We demonstrated that maternal infection and vaccination induced immunoglobulin concentrations in HM and that maternal stress negatively affected these immunoglobulin concentrations. In the last part of this thesis we demonstrated that maternal stress-associated changes in HM composition mediate the association between maternal postpartum stress and infant temperament, and reviewed the available scientific evidence for nutritional intervention to combat the adverse consequences of early-life/maternal stress.This thesis demonstrates the complex interplay of maternal stress, nutrition and immune status in contributing to the breastfed infant’s development through their effects on HM fatty acids, amino acids, oligosaccharides, microbiome and immunoglobulins. For an optimal understanding of how HM plays a role in the transmission of maternal factors to the child, it is crucial to consider HM as a complex biological system within the mother-milk-infant triad.