Charoenlarp 1988.

Methods	RCT. Series of treatment conditions.
Participants	325 pregnant women with Hb (AA) and 232 pregnant women with Hb (AE) attending midwife centres in 80 villages from the Varin Chamrab district of Ubon Province, Thailand. Chronic illness, complicated pregnancy, severe anaemia (Hb < 80 g/L), haemoglobinopathies Hb (EE) and (EF), and unwillingness to co‐operate were reason for exclusion. Individuals with Hb (AA) have normal Hb genes. Individuals with Hb (AE) have a heterozygous Hb E trait with normal Hb gene (A‐adults) and an abnormal Hb gene (E). This is usually a clinically insignificant condition.
Interventions	Participants were divided into 2 groups according to Hb (AA) and Hb (AE) and studied separately. Women from each group were randomly assigned to 1 of the following 11 interventions: group 1: placebo, supervised; group 2, 120 mg of elemental iron (as ferrous sulphate) and 5000 μg (5 mg) folic acid daily supervised; group 3, 240 mg of elemental iron (as ferrous sulphate) daily supervised; group 4: 240 mg of elemental iron (as ferrous sulphate) daily supervised; group 5: 120 mg elemental iron (as ferrous sulphate) and 5000 μg (5 mg) of folic acid, motivated but unsupervised; group 6: 240 mg of elemental iron (as ferrous sulphate) and 5000 μg (5 mg) of folic acid daily, motivated but unsupervised. For the Hb (AE) group, women were randomly assigned to 1 of the following groups: group 7: placebo, supervised; group 8: 240 mg elemental iron (as ferrous sulphate) and 5000 μg (5 mg) of folic acid daily, supervised; group 9: 240 mg of elemental iron (as ferrous sulphate) daily, supervised; group 10: 120 mg of elemental iron (as ferrous sulphate) and 5000 μg (5 mg) of folic acid daily, motivated but unsupervised; group 11: 240 mg of elemental iron and 5000 μg (5 mg) of folic acid daily, motivated but unsupervised. Starting and ending time of supplementation not stated. Setting and health worker cadre: the intervention was performed by community health workers under the supervision of a midwife and was delivered to the home of participants living in villages near Ubon, Thailand. Intervention was coordinated from village midwife centres.
Outcomes	Maternal: Hb, serum ferritin after 10 and 15 weeks of supplementation, and side effects.
Notes	Groups 1, 2, 3, 4, 7, 8, 9 supervised. Groups 5, 6, 10 and 11 motivated but unsupervised. For purposes of analysis, the groups were merged by iron alone or iron‐folic acid, and included as daily higher doses in both cases. Compliance not reported. Gestational age at start of supplementation: gestational age not specified. Anaemic status at start of supplementation: unspecified/mixed anaemia status. Daily iron dose: higher daily dose (60 mg or more of elemental iron). Iron release formulation: normal release preparation/unspecified. Iron compound: ferrous sulphate. Malaria setting: yes. As of 2011: Malaria: Malaria risk exists throughout the year in rural, especially forested and hilly, areas of the whole country, mainly towards the international borders, including the southernmost provinces. There is no risk in cities (e.g. Bangkok, Chiang Mai city, Pattaya), Samui island and the main tourist resorts of Phuket island. However, there is a risk in some other areas and islands. P. falciparum resistant to chloroquine and sulphadoxine–pyrimethamine reported. Resistance to mefloquine and to quinine reported from areas near the borders with Cambodia and Myanmar. 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)	Low risk	Set of random tables.
Allocation concealment (selection bias)	Unclear risk	Not described.
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Placebo controlled study but 2 of the groups had tablets under supervision (not blinded) and some of the tablets had an odd taste, so this may have affected compliance and reporting of side effects.
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Outcome assessment was only partially blinded and it is not clear what he impact of lack of blinding would be on some outcomes, although laboratory outcomes would be likely to be of low risk of bias.
Incomplete outcome data (attrition bias) All outcomes	Low risk	Ranged from 10% to 15%.
Selective reporting (reporting bias)	Unclear risk	There is insufficient information to permit judgement.
Other bias	Unclear risk	No other bias apparent.