Chisholm 1966.

Methods	RCT, 6 arms.
Participants	360 non‐anaemic women attending antenatal clinic at Radcliffe Infirmary, Oxford, United Kingdom before 28th week of gestation, who had not taken iron supplements in the preceding 8 weeks and with Hb >= 102 g/L or a normal serum iron reading. Exclusion criteria: Hb < 110 g/L and serum iron less than 60 μg/L.
Interventions	Participants were randomly assigned to 1 of various combinations of elemental iron as ferrous gluconate and folic acid, as follows: group 1: 900 mg elemental iron alone daily; group 2: 900 mg elemental iron and 500 μg (0.5 mg) folic acid daily; group 3: 900 mg elemental iron and 5000 μg (5 mg) folic acid daily; group 4: placebo; group 5: 500 μg (0.5 mg) folic acid daily; group 6: 5000 μg (5 mg) of folic acid daily. Iron and folic acid placebos were used. Supplementation started at 28th week until 40th week. Setting and health worker cadre: the intervention was performed by physicians at the antenatal clinic of The Radcliffe Infirmary, Oxford, United Kingdom.
Outcomes	Maternal: Hb, HCT, serum iron, serum folic acid activity, serum vitamin B12 estimation at 28 weeks of gestation and before delivery.
Notes	Unsupervised. For purposes of this review, placebo group was the group who received neither iron nor folic acid. Groups 2 and 3 were merged for iron‐folic acid comparisons. Compliance not reported. Gestational age at start of supplementation: late gestational age (from 28 weeks' gestation). Anaemic status at start of supplementation: non‐anaemic. Daily iron dose: higher daily dose (60 mg or more of elemental iron). Iron release formulation: normal release preparation/not specified. Iron compound: ferrous gluconate. Malaria setting: non‐malarial setting. As of 2011: Malaria: no risk.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	External randomisation.
Allocation concealment (selection bias)	Low risk	Bottles containing the tablets had been numbered by random selection at source and the code was unknown during trial.
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Double‐blind trial. Placebo‐controlled and placebo and active treatment described as indistinguishable. Bottles containing tablets were numbered and treatment allocation was not revealed until after the trial.
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Women with anaemia were treated (irrespective or allocation).
Incomplete outcome data (attrition bias) All outcomes	Low risk	No losses to follow‐up apparent.
Selective reporting (reporting bias)	Unclear risk	There is insufficient information to permit judgement.
Other bias	Unclear risk	No other bias apparent.