Batu 1976.

Methods	RCT, 4‐arm trial with individual randomisation.
Participants	133 women referred to investigators from a population of women attending an antenatal clinic for the fist time in Yangoon (also known as Rangoon), Myanmar (Burma). Women with severe anaemia were excluded from the trial during the intervention for treatment.
Interventions	Participants were randomly assigned to 1 of 4 groups starting at 22‐25 weeks: group 1: 60 mg of elemental iron (as ferrous sulphate), and 1 placebo tablets twice daily; group 2: 1 tablet containing 60 mg of elemental iron (as ferrous sulphate), and 1 tablet containing 500 μg (0.5 mg) of folic acid twice daily; group 3: 2 placebo tablets twice daily; group 4: 1 placebo tablet and 1 tablet containing 500 μg (0.5 mg) of folic acid twice daily. Administration of the treatments was carefully supervised. Supplementation started at 22‐25 weeks until term. Setting and health worker cadre: the intervention was performed by physicians at an antenatal clinic in Rangoon, Burma.
Outcomes	Maternal: Hb concentrations at baseline, at term (38‐40th week) and 4‐7 weeks postpartum, serum iron, serum and red cell folate activity and hypersegmented polymorph count at baseline, at 38‐40th week and postpartum.
Notes	Supervised. 32 women who had taken other supplements or whose Hb level at full term was not available were excluded from the analysis. 3 women from group 3 and 2 from group 4 developed severe anaemia and were also withdrawn from analysis. Gestational age at start of supplementation: late gestational age (more than 20 weeks at the start of supplementation) (22‐25 weeks' gestation). Anaemic status at start of supplementation: unspecified/mixed anaemia status at the start of supplementation (women with severe anaemia excluded). Daily iron dose: higher daily dose (60 mg elemental iron or more) (120 mg of elemental iron). Iron release formulation: normal release iron supplement/not specified. Iron compound: ferrous sulphate. Malaria setting: yes. As of 2011: Malaria risk due predominantly to P. falciparum exists throughout the year at altitudes below 1000 m, excluding the main urban areas of Mandalayand Yangon. Risk is highest in remote rural, hilly and forested areas. P. falciparum resistant to chloroquine and sulphadoxine–pyrimethamine reported. Mefloquine resistance reported in Kayin state and the eastern part of Shan state. P. vivax resistance to chloroquine reported. Human P. knowlesi infection reported.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Method not stated; "randomly placed in one of four treatment regimens".
Allocation concealment (selection bias)	Unclear risk	Insufficient information reported on the method used to conceal the allocation sequence.
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Placebo‐controlled trial so it is likely that staff and women were blind to allocation.
Blinding of outcome assessment (detection bias) All outcomes	Low risk	It was not clear whether those assessing outcomes were aware of allocation, but it is unlikely that this possible lack of blinding affected the laboratory outcomes reported.
Incomplete outcome data (attrition bias) All outcomes	High risk	37 women (28%) were excluded for analysis. 133 women randomised "32 women who had taken other hematinics or whose Hb level at full term was not available were excluded". 5 women developed anaemia and were given treatment. Loss was not balanced across groups.
Selective reporting (reporting bias)	High risk	32 women who had taken other supplements or whose Hb level at full term was not available were excluded from the analysis. 3 women from group 3 and 2 from group 4 developed severe anaemia and were also withdrawn from analysis.
Other bias	Low risk	No baseline imbalance apparent.