2.2. Enteral Nutrition 
weight gain, human milk
Mother’s own milk (MOM) was the exclusive source of enteral nutrition for study subjects. None of the subjects required pasteurized donor human milk in the 2 weeks prior to hindmilk fractioning or during the study. Weight-based enteral feeding tables were used as per our NICU guidelines, and daily feeding goals were posted at each infant’s bedside. Nutrient fortification commenced at 80 mL/kg/day, and parenteral nutrition was stopped once feeding volume reached 100–120 mL/kg per day and tolerance was observed. Fortification began at 1 package/50 mL human milk, and when the infant reached 100 mL/kg/day it was increased to 2 packages/50 mL human milk (approximately 0.78 kcal/mL). Similac Human Milk Fortifier Extensively Hydrolyzed Protein Concentrated Liquid (Abbott Nutrition, Tipp City, OH, USA) was used for nutrient enrichment. In infants with protein intake less than recommended values, Similac Extensively Hydrolyzed Protein Concentered Liquid (Abbott Nutrition, Tipp City, OH, USA) was prescribed at 0.5–1.5 g/kg/day amounts after nutrient fortification had reached 0.78 kcal/mL. Enteral feeds were further concentrated if weekly weight gain was <15 g/kg/day. Powdered hydrolyzed-protein formula (Nutramigen, Mead Johnson, Evansville, OH, USA) was prescribed to further concentrate feeds to approximately 0.92 kcal/mL (27 kcal/oz) as needed. Infants identified to have suboptimal growth velocity were followed daily by registered dietitians.Probiotics were prescribed in infants weighing ≥1000 g as per our NICU protocol. Standardized multivitamin drops were provided daily, containing 375 IU of vitamin A, 200 IU of vitamin D, and 17.5 mg of vitamin C, with an additional 400 IU of vitamin D until the infant reached 37 weeks corrected gestational age. Iron supplement was prescribed at 2–3 mg elemental iron/kg/day beginning at 14 days of life. All infants were weighed daily on electronic scales with a precision of 10 grams by nursing personnel, using the In-Bed scale (GiraffeTM OmniBedTM, Ohmeda Medical, Orang City, FL, USA). Other anthropometric measurements, length, and head circumference were taken by nursing personnel on admission and then weekly till discharge with a newborn length board (Length BoardsTM, Ellard Instrumentation Ltd., Monroe, MI, USA) and measuring tape, respectively. Infants were classified as being small for gestational age at admission to the NICU if they were below the 10th centile using Fenton’s Growth Curves [