Hoa 2005 (C).

Methods	Randomisation may have been by cluster (communes) rather than individual women. Block randomised trial with 4 arms.
Participants	202 apparently healthy pregnant women 20‐32 years of age attending health clinics from 12 communes in Dong HungDistrict, Thai Binh Province, Vietnam with 14‐18 weeks of gestation who agreed to participate in the study were selected to participate.
Interventions	Participants were assigned through block randomly assigned to 1 of 4 interventions: group 1 (n = 44) received 400 mL fortified milk with iron (ferrous fumarate), 17.5 mg vitamin C and 200 μg (0.2 mg) folic acid daily; group 2 (n = 41) received 400 mL of fortified milk containing 17.5 mg vitamin C and 200 μg (0.2 mg) folic acid but no iron daily; group 3 (n = 40) received 1 tablet containing 60 mg of elemental iron (as ferrous sulphate) and 250 μg (0.25 mg) folic acid daily; group 4 (n = 43) received 1 placebo tablet daily. Setting and health worker cadre: the intervention was performed by community health workers working from a commune health centre operated by the National Ministry of Health in the rural delta area of the Red River in northern Vietnam (Dong Hung District, Thai Binh Province).
Outcomes	Hb at baseline, 5, 10, 16 weeks after start of the study, total iron‐binding capacity, serum transferrin saturation, anaemia, iron deficiency, weight, presence of hookworms.
Notes	For purposes of this review groups 3 vs group 4 comparing iron and folic acid supplements are relevant. However, no data on outcomes of interest could be extracted from the published report. It was reported in the paper that the "decrease in haemoglobin concentration in the supplemented groups was significantly less"; and that, "the transferrin saturation level increased slightly in the supplement group". Gestational age at start of supplementation: early gestational age (supplementation started before 20 weeks' gestation). Anaemic status at start of supplementation: unspecified/mixed anaemia status. Daily iron dose: higher dose (60 mg of elemental iron). Iron release formulation: normal release preparation/unspecified. Iron compound: ferrous sulphate. Malaria setting: yes. As of 2011: Malaria risk due predominantly to P. falciparum exists in the whole country, excluding urban centres, the Red River delta, the Mekong delta, and the coastal plain areas of central Viet Nam. High‐risk areas are the highland areas below 1500 m south of 18˚N, notably in the 4 central highlands provinces Dak Lak, Dak Nong, Gia Lai and Kon Tum, Binh Phuoc province, and the western parts of the coastal provinces Khanh Hoa, Ninh Thuan, Quang Nam and Quang Tri. Resistance to chloroquine, sulphadoxine–pyrimethamine and mefloquine reported.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	It was not clear whether individual women or communes were randomised "For practical reasons it was possible to implement only 1 type of intervention per commune (block randomly adjusted)". It was not clear whether staff were aware of allocation before randomisation.
Allocation concealment (selection bias)	Unclear risk	Little information about study methods was provided.
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Partial blinding. Placebo preparations were provided. Described as single‐blind. Staff aware of allocation.
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Likely to be low risk for laboratory outcomes reported.
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	Loss to follow‐up not described. Not clear if any clusters were lost.
Selective reporting (reporting bias)	Unclear risk	There is insufficient information to permit judgement.
Other bias	Low risk	Groups appeared comparable at baseline. Data from this study were not included in the review.