Zinc supplementation during pregnancy in Bangladeshi women had no effect on birth weight

Although observational studies suggest a positive association between zinc status during pregnancy and pregnancy outcome, results of controlled supplementation trials have been mixed. We conducted a prospective double-blind intervention trial in a very poor urban Bangladesh community. 559 women were enrolled between 12-16 weeks gestation, stratified by parity and randomly assigned to two groups: 30 mg elemental zinc/day (n=269) or placebo (n=290). Supplementation continued until delivery and compliance with supplementation was 86%. Serum zinc and haemoglobin levels were estimated at baseline and at 7 months gestation, while anthropometries and dietary intake of the women was assessed monthly and morbidity weekly. Newborns were measured by a physician within 72 hours after birth and birth weights and gestational ages were known for 410 singleton infants. The overall incidence of low birth weight was 42.9% (45.9% in zinc supplemented vs 40.3% in placebo supplemented; p=0.27). Incidence of prematurity by LMP was 21.2% (22.7% in zinc supplemented vs 19.9% in placebo supplemented group; p=0.52). Means and distributions of birth weight, length at birth and head circumference at birth were not significantly different between the two groups. We conclude that antenatal supplementation with daily 30 mg elemental zinc alone has no apparent impact on birth outcome in this population.