Background: Preterm infants born 30 to 33 weeks' gestation often require early support with intravenous fluids because of respiratory distress, hypoglycemia or feed intolerance. When full feeds are anticipated to be reached within the first week, risks associated with intravenous delivery mode and type must be carefully considered. Recommendations are for parenteral nutrition to be infused via central venous lines (because of the high osmolarity), however, given the risks associated with central lines, clinicians may opt for 10% glucose via peripheral venous catheter when the need is short-term. We therefore compare a low osmolarity peripheral intravenous parenteral nutrition (P-PN) solution with peripheral intravenous 10% glucose on growth rate in preterm infants born 30 to 33 weeks' gestation. Methods: In this parallel group, single centre, superiority, non-blinded, randomised controlled trial, 92 (P-PN 42, control 50) infants born 30 + 0 to 33 + 6 weeks' gestation, were randomised within 24 h of age, to receive either P-PN (8% glucose, 30 g/L amino acids, 500 IU/L heparin and SMOFlipid®) or a control of peripheral intravenous 10% glucose. Both groups received enteral feeds according to hospital protocol. The primary outcome was rate of weight gain from birth to 21 days of age.