Menendez 1994 (C).

Methods	Cluster‐randomised trial, 2‐arm trial.
Participants	550 multi gravidae pregnant women with less than 34 weeks of gestation attending antenatal care clinics in 18 villages near the town of Farafenni, in North Bank Division, Gambia where malaria is endemic with high transmission during 4‐5 months a year.
Interventions	Participants were allocated randomly by compound of residence to receive 60 mg of elemental iron (as ferrous sulphate) or placebo. All pregnant women received a weekly tablet of 5000 μg (5 mg) of folic acid but no antimalarial chemoprophylaxis. Supplementation started at 23‐24 weeks until delivery. Setting and health worker cadre: the intervention was performed by traditional birth attendants in villages in the North Bank Division of The Gambia within the national village‐based primary healthcare program.
Outcomes	Maternal: Hb concentrations at baseline, 4‐6 weeks before delivery and 1 week postpartum; plasma iron, total iron binding capacity, transferrin saturation, deposition of malaria pigment in placenta. Infant: birthweight within 7 days of delivery.
Notes	Unsupervised. Malaria prophylaxis is provided to primigravidae in The Gambia. 30 women with PCV less than 25% after enrolment (17 in iron group and 13 in placebo) were treated and withdrawn from study and analysis. Additionally, 29 women (7 in iron and 22 in placebo group) had PCV below 25% at the second visit and were also withdrawn from study. No differences in the prevalence and severity of peripheral blood or placental malaria infection. No increase in the susceptibility to malaria infection in the 2 groups. Compliance: estimated tablet consumption was 81.1 and 81.7 tablets in the iron and placebo groups respectively. Gestational age at start of supplementation: late gestational age (more than 20 weeks' gestation at the start of supplementation). Anaemic status at start of supplementation: unspecified/mixed anaemia status. Daily iron dose: higher daily dose (60 mg daily). Iron release formulation: normal release preparation/unspecified. Iron compound: ferrous sulphate. Malaria setting: high malaria risk area. As of 2011: Malaria risk due predominantly to P. falciparum exists throughout the year in the whole country. Resistance to chloroquine and sulphadoxine–pyrimethamine reported.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Randomised but method unclear.
Allocation concealment (selection bias)	High risk	Not described. Active treatment and placebo were different colours.
Blinding of participants and personnel (performance bias) All outcomes	High risk	Partial blinding. This was a placebo‐controlled trial but the active and placebo supplements were different colours. Women were likely to be blind but staff may have been aware of allocation.
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Laboratory outcomes unlikely to have been affected by partial blinding.
Incomplete outcome data (attrition bias) All outcomes	High risk	More than 20% lost to follow‐up.
Selective reporting (reporting bias)	Unclear risk	There is insufficient information to permit judgement.
Other bias	Unclear risk	This was a cluster‐randomised trial, there was no clear baseline imbalance. Data in the original analysis were not adjusted for cluster deign effect but have been adjusted in this review.