A randomized, placebo-controlled trial of the effect of zinc supplementation during pregnancy on pregnancy outcome in Bangladeshi urban poor

Background: Maternal zinc supplementation has been suggested as a potential intervention to reduce the incidence of low birth weight in developing cou ntries. To date. placebo-controlled trials have all been performed in indus trialized countries and the results are inconsistent. Objective: The objective of this study was to evaluate whether zinc supplem entation in Bangladeshi urban poor during the last 2 trimesters of pregnanc y was associated with pregnancy outcome. Design: We conducted a double-blind, placebo-controlled trial in which 559 women from Dhaka slums. stratified by parity between 12 and 16 wk of gestat ion, were randomly assigned to receive 30 mg elemental Zn/d (n = 269) or pl acebo (n = 290). Supplementation continued until delivery. Serum zinc was e stimated at baseline and at 7 mo of gestation. Dietary intake was assessed at baseline and anthropometric measurements were made monthly. Weight, leng th, and gestational ages of 410 singleton newborns were measured within 72 h of birth. Results: At 7 mo of gestation, serum zinc concentrations tended to be highe r in the zinc-supplemented group than in the placebo group (15.9 +/- 4.4 co mpared with 15.2 +/- 4.3 mu mol/L). No significant effect of treatment was observed on infant birth weight (2513 +/- 390 compared with 2554 +/- 393 g; NS) or on gestational age, infant length, or head, chest, or midupper arm circumference. The incidence and distribution of low birth weight, prematur ity, and smallness for gestational age also did not differ significantly af ter zinc supplementation. Conclusions: Supplementation with 30 mg elemental Zn during the last 2 trim esters of pregnancy did not improve birth outcome in Bangladeshi urban poor . These results indicate that interventions with zinc supplementation alone are unlikely to reduce the incidence of low birth weight in Bangladesh.