Ziaei 2007.

Methods	RCT 2 arms with individual randomisation.
Participants	750 apparently healthy non‐smoking non‐anaemic (with Hb higher or equal to 132 g/L) pregnant women in early stage of second trimester, BMI 19.8‐26 kg/m2 and age 17‐35 years with singleton pregnancy attending prenatal care in Tehran, Iran. Women with history of threatened abortion in the present pregnancy or diseases related with polycythaemia such as asthma and chronic hypertension were not included.
Interventions	Participants were randomly assigned to 1 of 2 groups: group 1 received 50 mg of elemental iron (as ferrous sulphate) + 1000 μg (1 mg) folic acid daily; group 2 received placebo and 1000 μg (1 mg) of folic acid daily. Setting and health worker cadre: the intervention was performed by midwives and physicians at multiple urban clinical centres in Tehran, Iran.
Outcomes	Maternal: Hb at 24‐28 weeks, 32‐36 weeks, premature delivery, weight gain, caesarean sections, hypertensive disorders, severe anaemia, high Hb concentrations, iron deficiency, iron‐deficiency anaemia, MCV, MCH and MCHC at term, severe anaemia and high Hb concentrations at any time during 2‐3 trimesters, symptomatic tract infection, puerperal infection, antepartum and postpartum haemorrhage, transfusion provided, side effects (any), diarrhoea, constipation, nausea, heartburn, vomiting, placental abruption, premature rupture of membranes. Infant: birthweight, perinatal mortality rate, low Apgar at 10th minute, small‐for‐gestational age.
Notes	Unsupervised. Supplementation started 13.07 ± 2.02 weeks' gestation for group 1 and 13.66 ± 3.45 weeks' gestation for the placebo group and lasted until after delivery. No compliance reported. Gestational age at start of supplementation: early gestational age at the start of supplementation (supplementation started before 20 weeks' gestation). Anaemic status at start of supplementation: non‐anaemic. Daily iron dose: medium iron dose (50 mg elemental iron). Iron release formulation: normal release preparation/unspecified. Iron compound: ferrous sulphate. Malaria setting: yes. As of 2011: Malaria risk due toP. vivax and P. falciparum exists from March to November inclusive in rural areas of the provinces of Hormozgan and Kerman (tropical part) and the southern part of Sistan‐Baluchestan. P. falciparum resistant to chloroquine and sulphadoxine–pyrimethamine reported.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	By means of table of random numbers.
Allocation concealment (selection bias)	Low risk	Coded bottles.
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Participants and care provider and outcome assessor blinded.
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Participants and care provider and outcome assessor blinded.
Incomplete outcome data (attrition bias) All outcomes	Low risk	Less than 5% lost to follow‐up.
Selective reporting (reporting bias)	Unclear risk	There is insufficient information to permit judgement.
Other bias	Unclear risk	No other bias apparent.