Zinc supplementation during pregnancy and effects on growth and morbidity in low birthweight infants: a randomised placebo controlled trial

Abstract

Background: Infant malnutrition and mortality rates are high in less-developed countries especially in low-birthweight infants. Zinc deficiency is also widely prevalent in these circumstances. We aimed to assess the effect of daily zinc supplements given to pregnant mothers on their infants' growth and morbidity.

Methods: We did a double-blind, placebo controlled, randomised trial in 199 and 221 Bangladeshi infants whose mothers took 30 mg daily elemental zinc or placebo, respectively, from 12 to 16 weeks' gestation until delivery. Infants were followed up until 6 months of age. We obtained data for morbidity every week by mothers' recall. Infants' anthropometric measurements were done every month, and their serum zinc was assessed at 1 and 6 months of age.

Findings: Infants of mothers who received zinc during pregnancy had at age 6 months reduced risks compared with those in the placebo group for acute diarrhoea (risk ratio 0.84; 95% CI 0.72-0.98), dysentery (0.36; 0.25-0.84), and impetigo (0.53; 0.34-0.82). These reductions were seen in low-birthweight infants but not in those with normal birthweight. There were no differences in infant growth or serum zinc concentrations between treatment groups.

Interpretation: Maternal zinc supplementation during pregnancy resulted in a reduction of the health risks in Bangladeshi low-birthweight infants, although this intervention did not improve birthweight. Whether zinc should be added to usual antenatal supplements in regions with high rates of low birthweight should be reviewed.