Study design

Design: Four-group factorial, individually randomised placebo-controlled trial.

Allocation: Allocation concealed: randomisation was undertaken by a remote statistician. Pregnant women were assigned to iron and folic acid (active) or folic acid alone. Their newborns were allocated to iron or a placebo control.

Blinding: Supplements were delivered in identical dark bottles. Mothers and assessors were blinded.

Study question

Setting: Hebei, China. A community-based study randomising pregnant woman between June 2009 and December 2011and their babies between December 2009 and June 2011.

Patients: 1482 infants of 2371 women who had been randomised to iron supplementation or placebo during pregnancy, and whose cord ferritin <35 mg/L. Included babies were of singleton pregnancies enrolled <20 weeks gestation.

Intervention: 752 infants received 1 mg/kg iron and 730 placebo between 6 weeks and 9 months of age.

Outcomes: Gross motor development was assessed using the Peabody Developmental Motor Scale Second Edition. Secondary outcomes were neurological integrity …