The impact of gastrointestinal motility on feeding tolerance in the very preterm infant.

Infants who are preterm experience developmental arrest of the gastrointestinal system, which continues to mature throughout their neonatal intensive care hospitalization. During this period of development and clinical exposures, infants frequently experience episodes of enteral feeding intolerance. Currently, definitions of feeding intolerance are vague and fail to distinguish developmental feeding patterns from pathological feeding intolerance. In this review, we disentangle these entities by examining the physiology of the fetal and neonatal gut, the development of the microbiome, and factors that compound intestinal dysmotility. We will also review clinical, imaging, and biomarker approaches to the assessment of feeding intolerance. Finally, we propose a standardized, trajectory-based definition to support more consistent clinical care and enable future trials to use uniform definitions. Notably, this review will focus on the typical preterm infant trajectory, not infants at risk of intestinal failure.