Reid 2018.

Study characteristics
Methods	Parallel randomised controlled trial, single centre, with stratification by infant sex and gestational age
Participants	Inclusion criteria infants born 28–32 completed weeks' gestation whose mothers intended to provide breast milk Exclusion criteria major congenital or chromosomal abnormality likely to affect growth where protein therapy was contraindicated infants likely to transfer to remote locations and infants who had received standard practice human milk fortifier for > 4 days Setting: neonatology department Women's and Children's Hospital, Adelaide, Australia Timing: February 2012 to May 2013
Interventions	Intervention: bovine based human milk fortifier containing 1.8 g extensively hydrolysed protein added to 100 mL EBM (n = 31) Control: bovine based human milk fortifier containing 1 g extensively hydrolysed protein added to 100 mL EBM (n = 29) Calorie content: isocaloric, 21 kcal energy added to 100 mL EBM Start of intervention: within 1 or 2 days after randomisation Mean age at study entry: 8.9 days (SD 3.2) in intervention group and 9.0 days (SD 2.5) in control group End of intervention: until removal of the nasogastric tube or estimated date of delivery
Outcomes	Primary outcome rate of weight gain Secondary outcomes length and head circumference gain small for gestational age and body composition feeding tolerance biochemical analysis (blood urea nitrogen, plasma albumin, plasma creatinine, pH and base deficit measured, amino acids)
Notes	Conflict of interest: MM serves on scientific advisory boards for Fonterra and Nestle. Source of funding: a Women's and Children's Hospital Foundation Grant funded the research. Nestle Nutrition and Nutricia donated human milk fortifiers and supplements used in this study. Unpublished data regarding weight gain as g/kg/day were sought and used.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	An independent researcher created the randomisation schedule using a computer generated variable block design of 4 and 6
Allocation concealment (selection bias)	Low risk	Upon consent, infants were randomised by telephoning an independent researcher who held the randomisation schedule and assigned a unique study identification number
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Participants, clinicians, outcome assessors and data analysts were blinded to randomisation group.
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Clinicians, outcome assessors and data analysts were blinded to randomisation group.
Incomplete outcome data (attrition bias) All outcomes	Low risk	All infants were accounted for in the analyses, 2 infants in each group discontinued intervention but their data were included.
Selective reporting (reporting bias)	Unclear risk	Insufficient information.
Other bias	Low risk	Trial product was donated by manufacturer, who was not further involved in the trial.