BackgroundPreterm infants' meals typically progress to higher volumes over time. Knowledge of gastric emptying (GE) responses to differing meal volumes may inform enteral feeding management. We examined the effect of meal volume and composition on preterm GE.MethodsForty infants were studied at 33.3±1.4 (29.7-35.6) weeks postmenstrual age when fully enteral fed (target 150 ml/kg/day). Intraindividual comparisons of GE were made for paired meals of 100% and 75% prescribed volume and identical composition of mother's own milk (n=21) and pasteurized donor human milk (n=19). Serial stomach ultrasound images were used to calculate gastric residual volumes (GRVs) and remaining meal proportions (% meal).ResultsGE was faster in the early postprandial period and slowed over time (P<0.001). Reduced volume meals had slower GE rates and lower GRV (P<0.001). Serial postprandial % meal was similar between reduced and full volume meals (P=0.41). Higher milk casein concentration was associated with slower GE (P=0.04). Complete gastric emptying (GRV=0 ml) was more common in infants fed at 3 h intervals compared with those fed every 2 h (P=0.002).ConclusionEarly postprandial GE is more rapid for larger meal volumes. Stable preterm infants may tolerate feeding of a 3 h meal volume at shorter intervals.