What are the Effects of Premature Birth on the Infant Gut Microbiome?

premature birth

Short and long-term effects of premature birth can lead to poor health outcomes in infants. This study investigates the effects of premature birth on the infant gut microbiome, and its association with growth, medication intake, and overall health.

Infants born before 37 weeks gestation, or preterm infants, experience increased short-term complications including respiratory and cardiovascular issues, as well as long-term health conditions. Nutrition in early life is critical for neonatal growth and long-term health, however, optimizing nutrition and feeding regimes for preterm infants is currently a clinical challenge. More than 50% of preterm infants are discharged from the hospital with ongoing severe postnatal growth failure, which contributes to long-term health. Understanding the variables that contribute to poor outcomes can alleviate the health effects of premature birth on infants.

The Gut Microbiome May Play a Role in Infant Health

Scientists now understand that the infant gut microbiome – the collection of microorganisms inhabiting the digestive tract – directly contributes to the growth and physiological development of preterm infants. Gut microbiota have important roles in breaking down food that humans cannot metabolize on their own, producing vitamins, and proper immune function. In infants, the gut microbiome progressively develops through three distinct phases strongly associated with gestational age.

The environment in the neonatal intensive care unit (NICU), infant nutrition, and common clinical practices are important in gut microbiome development, particularly in preterm infants. A study published in Microbiome investigates the relationship between gestational age, gut microbiota, nutritional intake, medication, and growth in preterm infants to study the effects of premature birth.

Researchers studied two cohorts, one containing predominately preterm infants and the other containing full-term infants only. Researchers determined gut microbiome composition by conducting rectal swabs on infants multiple times per week to determine the microbial composition of phases and the timing of phase-switches. Researchers found that each microbiome phase has different functional capacities related to nutrient processing requirements and microbiota-derived metabolites. Researchers related gut microbiome to neonatal growth, nutrition, and clinical practices.

The Effects of Premature Birth on the Gut Microbiome

Researchers found that the microbiome of preterm infants was less diverse than full-term infants, subjecting preterm infants to a greater risk of developing a microbial imbalance due to physiological and immune maturity in preterm infants. This immaturity disrupts the progression of the gut microbiota through the three phases.

Gut microbiota phase succession was also dependent on the administration of medication including broad-spectrum antibiotics, gut motility agents, and corticosteroids –all common medications administered to preterm infants. In general, medication delayed microbiome phase succession which is detrimental to postnatal growth and long-term health. Further, postnatal growth in infants is strongly associated with nutrition, specifically total caloric intake and feeding through the mouth versus IV, with mouth-feeding being more beneficial.

This is the first-ever study to demonstrate the association between gut microbiota phase, nutrition, and growth in preterm infants. Broadly, the healthy growth of infants and rapid gut development occur simultaneously, and this study found that prematurity in infants hinders this process. However, this important study identified a therapeutic avenue that may alleviate the effects of premature birth – the gut microbiome, as a healthy gut microbiome in infants facilitates healthy growth and development.

More research may lead to personalized microbiome care in preterm infants, improved clinical guidelines concerning infant nutrition, and medication to optimize growth and mitigate pathologies in preterm infants. Progress in understanding interactions between humans and their gut microbiomes will improve both short- and long-term health outcomes for preterm infants.

Written by Mallory Wiggans

Reference: Grier, A. et al. Impact of prematurity and nutrition on the developing gut microbiome and preterm infant growth. Microbiome 5:158 (2017).

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