Intestinal oxygenation, growth, and development of preterm infants

In this thesis, we focused on preterm infants, i.e. infants born with a gestational age below 37 weeks. Preterm birth may disrupt maturation of the intestine and the brain, and increase the risk of growth faltering and developmental problems. We aimed to gain more insight in the relation between intestinal oxygenation, i.e. the level of oxygen in intestinal tissue, growth, and development in preterm infants. First, we demonstrated that preterm infants are susceptible to a shortage of oxygen in the intestine, due to immature mechanisms that regulate intestinal oxygenation and a smaller reserve for changes in oxygen supply and oxygen demand. Then, we showed that near-infrared spectroscopy is a valid tool for monitoring of intestinal oxygenation. To correctly interpret these measurements, gestational age, birth weight relative to gestational age, and postnatal age need to be taken into account. Next, we showed that reduced variability of intestinal oxygenation is associated with changes in expression of selected genes, suggestive of intestinal injury. We did not find a relation between intestinal oxygenation and growth, although we speculate that reduced variability of intestinal oxygenation is also associated with poorer growth. Finally, we demonstrated that growth is associated with several domains of development. Promoting growth may, thus, lead to better developmental outcomes. We hope that our results may contribute to the implementation of intestinal oxygenation monitoring using near-infrared spectroscopy in clinical care. Ultimately, we believe this may lead to more personalized care practices and better growth and developmental outcomes in preterm infants