Sun 2010.

Methods	Double‐blind RCT.
Participants	Inclusion criteria: anaemic (Hb > 80 but < 110g/L); pregnant women, 12‐24 weeks' gestation, age between 20‐30 years; no dietary supplements during previous 2 months; no abnormal pregnancy response.
Interventions	4 groups: group 1 (n = 47) was supplemented daily with 60 mg iron as ferrous sulphate; group 2 (n = 46) with 60 mg and 0.4 mg folic acid; group 3 (n = 46) with 60 mg iron, 2.0 mg retinol and 0.4 mg folic acid; group 4 (n = 47) was the placebo control group.
Outcomes	Primary outcomes: iron status; Cytokine Interleukin ‐2 (IL ‐2) levels; Lymphocyte proliferation.
Notes	Short intervention time of 2 months duration. Patient were recruited between March 2004 ‐ September 2005. Setting: Shen county in a central rural area of China. Total number of patients ‐ 186.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	High risk	"Patients were randomised in order of enrolment."
Allocation concealment (selection bias)	High risk	"Patients were randomised in order of enrolment."
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Adequate blinding of participants and personnel reported.
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	No details given.
Incomplete outcome data (attrition bias) All outcomes	Low risk	Loss of participants < 5% ‐ 6 women did not complete the trial due to moving to other villages (3), and stopped taking supplements during the trial (3).
Selective reporting (reporting bias)	Unclear risk	No details given.
Other bias	Unclear risk	No details given.