In preterm neonates, parenteral nutrition (PN) is utilized to provide adequate energy and maintain the expected growth rate of a fetus. To optimize growth, our institution implemented comprehensive guidelines for prescribing PN. This study compared the effect of this change on growth outcomes of very low-birth-weight (VLBW) infants at 28 days' postnatal age (PNA). Neonates <1250 g who received PN for >7 days were divided into preimplementation and postimplementation cohorts based on date of birth. The primary objective was to compare the average weight velocity (g/kg/day) of neonates at 28 days' PNA. Secondary objectives included identifying the average number of days to regain birth weight and comparing the percentage of infants above the 10th percentile for weight for age at 28 days with those at baseline. There were 204 neonates in cohort 1 (before implementation) and 176 neonates in cohort 2 (after). No difference in weight velocity was identified (12.9 ± 5.2 vs 12.1 ± 4.9 g/kg/day; P = .177). No difference was detected in days to regain birth weight (9.2 ± 4.6 vs 9.9 ± 4.7; P = .909) or in the percentage of patients above the 10th percentile for weight for age (birth: 85.3% vs 83.5% [P = .634]; 28 days: 73% vs 64.8% [P = .082]). No difference was observed in the weight velocity of VLBW neonates <1250 g at birth when using the implemented guideline for PN prescription writing at our institution.