Groner 1986.

Methods	RCT, 2 arms, individual randomisation.
Participants	40 pregnant women attending antenatal care at the Adolescent Pregnancy Clinic and Obstetrics Clinics at the John Hopkins and Sinai Hospital in Baltimore, Maryland, USA at or before 16 weeks of pregnancy with HCT equal or above 31%. 2 women objected to the randomisation and 13 dropped out of the study. Both groups received multiple micronutrients. Supplementation lasted a month.
Interventions	Participants were randomly assigned to 1 of 2 groups: group 1 (n = 16) received 60 mg of elemental iron (as ferrous fumarate) and prenatal vitamins daily; group 2 (n = 9) received only the prenatal vitamins with no iron. Setting and health worker cadre: the intervention was performed by physicians at the Adolescent Pregnancy Clinic and Obstetrics Clinic of Johns Hopkins and Sinai Hospitals in Baltimore, Maryland, United States of America.
Outcomes	Psychometric tests (arithmetic, total digit span, digit symbol, vocabulary and others) were performed and haematologic status was measured at baseline and after a month.
Notes	Haematologic outcomes cannot be extracted from the paper. None of the other outcomes were sought. Gestational age at start of supplementation: early gestational age (supplementation started before 20 weeks' gestation). Anaemic status at start of supplementation: mixed/unspecified anaemia status. Daily iron dose: higher daily dose (60 mg or more elemental iron). Iron release formulation: normal release preparation/unspecified. Iron compound: ferrous fumarate. Malaria setting: non‐malarial setting. As of 2011: Malaria: no risk.
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Not described.
Allocation concealment (selection bias)	Unclear risk	Not described.
Blinding of participants and personnel (performance bias) All outcomes	Low risk	"Each subject was handed an unlabeled bottle of capsules... The test administrator was also unaware of the content of the capsules distributed."
Blinding of outcome assessment (detection bias) All outcomes	Low risk	It was stated that the test administrator was not aware of the treatment group.
Incomplete outcome data (attrition bias) All outcomes	High risk	15 of the 40 women randomised were not followed up. Group size at follow‐up was not balanced (16 vs 9).
Selective reporting (reporting bias)	Unclear risk	There is insufficient information to permit judgement.
Other bias	Unclear risk	No other bias apparent.