The effect of zinc supplementation on pregnancy outcomes: a double-blind, randomised controlled trial, Egypt

Abstract

The present randomised controlled trial (RCT) was conducted to evaluate the effect of two regimens of Zn supplementation on pregnancy outcomes in Alexandria, Egypt. Healthy pregnant women aged 20–45 years and having low serum Zn level below the estimated median for the gestational age were eligible to participate in the trial. Of 1055 pregnant women assessed for the eligibility of low serum Zn level, 675 were eligible. These women were randomly assigned to one of the three groups: the Zn alone group (n 225) received a daily dose of 30 mg ZnSO4, the combined group (n 227) received 30 mg ZnSO4 plus multivitamins (B1, B6, D3, C and E) and the control group (n 223) received placebo (270 mg lactose). They were followed up from the time of recruitment till 1 week after delivery. Overall, there was no detectable difference in the mean birth weight between the three groups (mean 2929.12 (SD 330.28), 2922.22 (SD 324.05) and 2938.48 (SD 317.39) g for the placebo, Zn and Zn plus multivitamin groups, respectively, P = 0.88). Both the single and the combined Zn supplements were almost equally effective in reducing second- and third-stage complications (relative risk (RR) 0.43, 95% CI 0.31, 0.60 for the Zn group and RR 0.54, 95% CI 0.40, 0.73 for the combined group). Stillbirth and preterm delivery were significantly lower among the two supplemented groups than the placebo group (P = 0.001). Early neonatal morbidity was also significantly lower in the supplemented groups (RR 0.23, 95% CI 0.15, 0.35 for the Zn group and RR 0.25, 95% CI 0.16, 0.37 for the combined group). Collectively, Zn supplementation was effective in reducing pregnancy complications and early neonatal infection among the Zn-deficient women of the present trial.