Impact of maternal prenatal psychosocial stress and maternal obesity on infant microbiota

The prenatal period is a critical window of development for all major physiological systems in the human body. During pregnancy, maternal prenatal psychosocial stress (PNS) and maternal obesity are identified as risk factors for infant and child health. Several possible mechanisms have been suggested to explain this link, including the transfer of maternal microbiota to offspring. PNS and maternal obesity may negatively affect maternal microbiota during pregnancy. By means of maternal microbial transfer in utero and at birth, PNS and maternal obesity could negatively affect the offspring’s gut microbial colonisation. During delivery infants will come in contact with maternal vaginal and gut microbiota, and a spurt in infant gut colonisation will commence. Appropriate colonisation and gut microbiota development in new-borns are important for gut health, and therefore for child health and development. Results from animal and human studies show that PNS can affect the infant microbial composition. These findings need to be confirmed in large prospective cohort studies. In addition, a number of human studies indicate that maternal obesity may alter maternal gut microbiota and through vertical transfer of obesogenic maternal microbes may consequently predispose offspring to obesity. The relevance of these maternal obesogenic microbes in the infant’s gut for weight trajectory over the life course requires further evaluation. In this chapter, we will review the current understanding of how PNS and maternal pregnancy obesity may affect maternal gut microbiota and consequently infant microbiota and health. We will also discuss recent findings concerning proposed mechanisms of action. Finally, we will offer recommendations for clinical practice and future research.