Sun 2010.

Methods	Quasi‐randomised trial with individual assignment in order of enrolment.
Participants	186 anaemic pregnant women, 12 to 24‐weeks' gestation, age between 20‐30 years with Hb concentration ≥ 80 and < 110 g/L, no dietary supplements during the previous 2 months and no abnormal pregnancy response from the communities of Shen County in a central rural area of China.
Interventions	Participants were randomly allocated in the order of enrolment to 1 of 4 groups: group 1 (n = 47) was supplemented daily with 60 mg elemental iron (as ferrous sulphate); group 2 (n = 46) received with 60 mg elemental iron (as ferrous sulphate) and 400 μg (0.4 mg) folic acid; group 3 (n = 46) with 60 mg elemental iron (as ferrous sulphate), 2 mg retinol and 400 μg (0.4 mg) folic acid; group 4 (n = 47) was the placebo control group. The capsules were coloured red, yellow, green and blue during manufacture by Hurun (a Chinese food‐additive company, Beijing). The capsules were to be taken daily for 2 months. Setting and health worker cadre: the study was carried out in communities of Shen County in a central rural area of China. Women were home‐visited once a week by the village nurse to replenish supplements and to monitor compliance by counting and recording the number of supplements that were taken.
Outcomes	Hb concentration; plasma iron; plasma retinol and plasma folate; erythrocyte protoporphyrin; interleukin 2; lymphocyte proliferation at baseline and after 2 months intervention.
Notes	Relevant comparisons for this review: group 1 (n = 47) was supplemented daily with 60 mg elemental iron (as ferrous sulphate) vs group 4 (n = 47) was the placebo control group. group 2 (n = 46) received with 60 mg elemental iron (as ferrous sulphate) and 400 μg (0.4 mg) folic acid vs group 4 (n = 47) was the placebo control group. Gestational age at start of supplementation: mixed gestational age at the start of supplementation (12‐24 weeks' gestation). Anaemic status at start of supplementation: anaemic at the start of supplementation (Hb < 110 g/L). Daily iron dose: higher daily dose (60 mg elemental iron). Iron release formulation: normal release preparation/not specified. Iron compound: ferrous sulphate. Malaria setting: yes. As of 2011: Malaria risk, including P. falciparum malaria, exists in Yunnan and to a lesser extent in Hainan. P. falciparum resistance to chloroquine and sulphadoxine–pyrimethamine reported. Limited risk of P. vivax malaria exists in southern and some central provinces, including Anhui, Ghuizhou, Henan, Hubei, Jiangsu. There is no malaria risk in urban areas. Supported by Danone Nutrition Institute China.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Reported as randomly assigned but method unclear. It is reported that the assignment to the groups was done in order of enrolment.
Allocation concealment (selection bias)	High risk	The capsules were coloured red, yellow, green and blue during manufacture and the assignment was done in order of enrolment.
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Participants, care providers and outcome assessors were blinded to the intervention groups.
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Participants, care providers and outcome assessors were blinded to the intervention groups.
Incomplete outcome data (attrition bias) All outcomes	Low risk	Low losses to follow‐up and they were balanced among the groups.
Selective reporting (reporting bias)	Unclear risk	There is insufficient information to permit judgement.
Other bias	Low risk	There were no substantial differences between the groups in any of the baseline characteristics.