Rolschau 1979.

Methods	This was a controlled trial conducted on women attending antenatal clinic of Odense University Hopsital. The criteria for selecting women was Danish birth and a normal pregnancy. Women were matched on parity, tobacco consumption, pre‐pregnant weight, housing condition and age.
Participants	Pregnant women in 21 to 25 week of gestation (n = 36).
Interventions	Group1: iron 250 mg (n = 16), group 2: iron 250 mg + folic acid 5 mg (n = 20).
Outcomes	Birthweight.
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Quote: "Subjects were allotted to two groups".
Allocation concealment (selection bias)	Low risk	Quote: 'groups were supplied similar tablets". Comment: probably done.
Blinding (performance bias and detection bias) All outcomes	Unclear risk	Insufficient information to make any judgement.
Incomplete outcome data (attrition bias) All outcomes	Low risk	Number excluded nor its reasons mentioned. Attrition (10%) was reported but reasons were not described.
Selective reporting (reporting bias)	Unclear risk	Insufficient information to make any judgement.
Other bias	Unclear risk	No other bias identified but insufficient information available to fully assess this 'Risk of bias' domain.