Principles in cellular oxygenation: fetal and neonatal intestines.

Complex biochemical consequences are the result of a series of secondary biochemical changes caused by oxygen depletion. Hypoxia in the fetus and neonate results in decreased GI blood flow, especially to the GI mucosa. Although severe O2 deprivation cannot be entirely compensated for, an increase in tissue O2 extraction does occur in cases of moderate hypoxemia. In the neonate increased demands for O2 during feedings result in increased blood flow. The occurrence of hypoxia during feedings causes a decrease in intestinal motility, suggesting a clinical correlate to feeding intolerance and increased vulnerability to necrotizing enterocolitis.