Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk
Allocation concealment (selection bias)	Unclear risk
Blinding of participants and personnel (performance bias)	Unclear risk
Blinding of outcome assessment (detection bias)	Unclear risk
Incomplete outcome data (attrition bias)	Unclear risk
Selective reporting (reporting bias)	Unclear risk
Other bias	Unclear risk
Was the allocation sequence adequately generated?	High risk	Quote: “It was not possible to use a randomised design of supplemented vs control subjects because of the relatively small number of births in Keneba”
		Comment: Study design did not permit randomisation to take place
Was the allocation adequately concealed?	Unclear risk	Comment: Insufficient information to permit judgement
Were baseline outcome measurements similar?	Low risk	Comment: Baseline outcomes were similar across groups
Were baseline characteristics similar?	Low risk	Comment: Baseline characteristics were similar across groups
Were incomplete outcome data adequately addressed?	Low risk	Quote: “Birthweights were unobtainable in three cases pre‐supplement and two cases post‐supplement because of referral for hospital deliveries”
Was knowledge of the allocated intervention adequately prevented during the study?	Unclear risk	Comment: Insufficient information to permit judgement
Was the study adequately protected against contamination?	Low risk	Comment: No blinding but the outcomes are not likely to be influenced by lack of blinding
Was the study free from selective outcome reporting?	Unclear risk	Comment: Published protocol not found. The outcomes specified in the methodology section have been reported in the results section
Was the study free from other risk of bias?	Low risk	Comment: No other potential sources of bias reported