Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: "Randomization was conducted according to a random computer‐determined allocation order considering gestational age"
		Comment: Most likely done
Allocation concealment (selection bias)	Unclear risk	No clear information available for allocation concealment
Blinding of participants and personnel (performance bias)	Low risk	Quote: "Blinding was possible because the nurses who administered L. reuteri to the infants were not involved in the daily care and the attending neonatal team was unaware of the randomization assignments"
Blinding of outcome assessment (detection bias)	Unclear risk	It was not clear if the families of the participating neonates were aware of the treatment assignments
Incomplete outcome data (attrition bias)	Low risk	About 18% attrition reported that was balanced in two groups
Selective reporting (reporting bias)	Low risk	Authors seem to report all the relevant outcomes
Other bias	Low risk	No other risk of bias was noted