Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: “MINIMat was a randomised controlled field trial with a 2×3×2 factorial design”
		Comment: Adequately done
Allocation concealment (selection bias)	Unclear risk	Comment: Insufficient information to permit judgement
Blinding of participants and personnel (performance bias)	Unclear risk	Comment: Insufficient information to permit judgement
Blinding of outcome assessment (detection bias)	Unclear risk	Comment: Insufficient information to permit judgement
Incomplete outcome data (attrition bias)	High risk	Quote: “One hundred and thirteen women had temporarily moved to another location outside of Matlab for the pregnancy and birth; 11 had permanently moved; 20 were absent from their homes and no one reported where they had gone; two women refused to participate; two women had measles; and 111 had either miscarried, dropped out”
		Comment: 259/1300 × 100 = 19.9% lost to follow‐up
Selective reporting (reporting bias)	Low risk	Comment: Outcomes mentioned in the protocol were reported (ISRCTN16581394)
Other bias	Low risk	Comment: No other potential sources of bias reported
Was the allocation sequence adequately generated?	Unclear risk
Was the allocation adequately concealed?	Unclear risk
Were baseline outcome measurements similar?	Unclear risk
Were baseline characteristics similar?	Unclear risk
Were incomplete outcome data adequately addressed?	Unclear risk
Was knowledge of the allocated intervention adequately prevented during the study?	Unclear risk
Was the study adequately protected against contamination?	Unclear risk
Was the study free from selective outcome reporting?	Unclear risk
Was the study free from other risk of bias?	Unclear risk