Metz 1965.

Methods	This RCT was conducted at the antenatal clinic at South Rand Hospital, Johannesburg, South Africa.
Participants	A total of I75 pregnant white women attending the clinics were selected.
Interventions	Group 1: 200 mg of iron orally daily, either as ferrous sulphate or ferrous fumarate (n = 57). Group 2 iron as in group 1 together with 5 mg of folic acid orally daily (n = 60). Group 3 vitamin B12 orally (daily in addition to iron and folic acid as in group 2 (n = 58).
Outcomes	Urinaru FIGLU (n = 175), serum folate activity, serum vitamin B12 concentration, serum haemoglobin and haematocrit (n = 175).
Notes	In this review group 1 was compared with group 2.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Quote: "patients were randomly allocated to one of three groups...".
Allocation concealment (selection bias)	Unclear risk	Insufficient information to permit judgement.
Blinding (performance bias and detection bias) All outcomes	Unclear risk	Quote: "All tablets were dispensed in identical gelatin capsules". Comment: insufficient information to permit judgement.
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Insufficient information to permit judgement.
Selective reporting (reporting bias)	Unclear risk	Insufficient information to permit judgement.
Other bias	Unclear risk	No other bias identified but insufficient information available to fully assess this 'Risk of bias' domain.