BackgroundNew standardised parenteral nutrition (SPN) formulations were implemented in July 2011 in many neonatal intensive care units in New South Wales following consensus group recommendations. The aim was to evaluate the efficacy and safety profile of new consensus formulations in preterm infants born less than 32 weeks.MethodsA before-after intervention study conducted at a tertiary neonatal intensive care unit. Data from the post-consensus cohort (2011 to 2012) were prospectively collected and compared retrospectively with a pre-consensus cohort of neonates (2010).ResultsPost-consensus group commenced parenteral nutrition (PN) significantly earlier (6 v 11 hours of age, p 0.005). In comparison to the pre-consensus cohort, there was a higher protein intake from day 1 (1.34 v 0.49 g/kg, p 0.000) to day 7 (3.55 v 2.35 g/kg, p 0.000), higher caloric intake from day 1 (30 v 26 kcal/kg, p 0.004) to day 3 (64 v 62 kcal/kg, p 0.026), and less daily fluid intake from day 3 (105.8 v 113.8 mL/kg, p 0.011) to day 7 (148.8 v 156.2 mL/kg, p 0.025), and reduced duration of lipid therapy (253 v 475 hr, p 0.011). This group also had a significantly greater weight gain in the first 4 weeks (285 v 220 g, p 0.003).ConclusionsNew consensus SPN solutions provided better protein intake in the first 7 days and were associated with greater weight gain in the first 4 weeks. However, protein intake on day 1 was below the consensus goal of 2 g/kg/day.Electronic supplementary materialThe online version of this article (doi:10.1186/s12887-014-0309-0) contains supplementary material, which is available to authorized users.