AbstractBackgroundDuring NICU admission, extra-uterine growth retardation that can affect the neurodevelopmental outcome is a challenging problem in extremely preterm infants. This trial aimed to determine the effect of additional enteral protein supplementation on the growth velocity of the anthropometric parameters.MethodIn this randomized controlled trial, 77 preterm infants (gestational age ≤33 weeks and birth weight <1500 g) who reached full enteral feeding with either fortified breast milk or preterm formula were included. They were randomized to receive either 4-<5 g/kg/day protein through extra protein supplementation (intervention) or 3-<4 g/kg/day protein. Weight gain, as well as length and head circumference growth, were monitored daily and weekly, respectively. Venous blood gas, blood urea nitrogen (BUN), and albumin levels were checked weekly.ResultsFive out of 77 participants were excluded due to feeding intolerance. Analyses were conducted on 36 neonates with protein intake of 3.66 ± 0.22 gr/kg/day and 36 with extra protein intake. Baseline characteristics were similar between the groups. An additional protein supply of 0.89 gr/kg/day, resulting in an average protein intake of 4.55 ± 0.18 in the intervention group, increased the postnatal weight gain, linear growth, and head circumference growth (7.98 gr/kg/day, 0.347 cm/week, and 0.38 cm/week, respectively). The albumin levels were significantly increased, but the BUN levels were not significantly increased in the intervention group. None of the patients developed necrotizing enterocolitis or significant acidosis.ConclusionProtein supplementation significantly improves the growth of the anthropometric parameters. An increase in serum albumin and no increase in serum urea can indicate the anabolic effect of extra protein. Protein supplementation can add to routine feeding protocols of VLBW infants without any short-term adverse effect; however, further study for evaluation of long-term complications is needed.