Foulkes 1982.

Methods	Quasi‐randomised trial, 2 arms with individual randomisation.
Participants	568 apparently healthy pregnant women with less than 20 weeks of pregnancy and no prior iron supplementation.
Interventions	Participants were allocated alternatively to receive 100 mg of elemental iron and 350 μg (0.35 mg) folic acid daily or no treatment.
Outcomes	Ferritin and Hb concentrations were measured at baseline and at 28 and 36 weeks of gestation and 2 days postpartum. MCV and MCH were measured at 2 days postpartum. Number of women developing anaemia in the 2nd and 3rd trimester was reported (Hb < 105 g/L). Setting and health worker cadre: the intervention was performed by obstetricians at Southmead Hospital in Bristol, United Kingdom.
Notes	Only means and median are presented for continuous outcomes. No SDs are reported and for ferritin concentrations no ln‐transformed data are presented. Limited data were extractable from the paper and subsequent communication with the author. The paper reported the number of women developing Hb < 105 g/L from the start of supplementation to delivery. No data were extracted from this trial. Gestational age at start of supplementation: early gestational age (supplementation started before 20 weeks' gestation). Anaemic status at start of supplementation: mixed/unspecified anaemia status. Daily iron dose: higher daily dose (60 mg or more elemental iron). Iron release formulation: normal release preparation/unspecified. Iron compound: not clear. 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)	High risk	Alternation.
Allocation concealment (selection bias)	High risk	Alternate allocation.
Blinding of participants and personnel (performance bias) All outcomes	High risk	No blinding. No placebo.
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Women who did not comply or who became anaemic were treated. Outcomes reported unlikely to be affected by lack of blinding.
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	537 women randomised, then 67 excluded post‐randomisation for reasons that may have related to outcomes (non‐compliance). Subsequent loss to follow‐up was not clear as denominators were not reported in the text or figures.
Selective reporting (reporting bias)	Unclear risk	There is insufficient information to permit judgement.
Other bias	Unclear risk	No other bias apparent.