Poor maternal zinc status is associated with adverse pregnancy outcome in many observational studies and in early randomized trials with various methodologic limitations. In a trial among African-American women with low plasma zinc concentrations, prenatal zinc supplementation resulted in a significant increase in birth weight and in longer duration of pregnancy. The results suggest that zinc supplementation may be beneficial in developing countries, where pregnant women may be more likely to have suboptimal zinc intakes. No maternal zinc trial has been carried out in African settings, where HIV infection is prevalent. Apart from its potential effects on pregnancy outcome, the relations between zinc status and HIV-related outcome are controversial.

Investigators enrolled HIV-infected pregnant women in Africa to examine the efficacy of zinc supplements on birth outcomes, including fetal death, birth weight, and duration of pregnancy. Eligibility required an estimated gestational age at randomization of between 12 wk and 27 wk. Women received a daily oral dose of one of the two interventions from enrollment until the end of the study at 6 wk postpartum: a) 25 mg Zn as zinc sulfate included in an effervescent citrus-flavored tablet or b) a similarly constituted zinc-free placebo. Demographic information was obtained at the first visit. Also, at baseline and every month thereafter, a study physician conducted a full physical examination, and a research nurse gathered information on health problems during the prior month and obtained anthropometric measurements. The primary endpoint of the trial was to examine the effect of zinc supplementation on hemoglobin concentrations between enrollment and 6 wk postpartum.

Researchers observed no significant differences in birth weight, duration of gestation, or fetal and neonatal mortality between women in the zinc and placebo groups. Hemoglobin concentrations increased between baseline and 6 wk postpartum in both groups. However, the rise in hemoglobin over this period was significantly lower (P = 0.03) in the zinc group than in the placebo group. Similarly, the changes in red blood celt count and in packed cell volume over the same period were significantly lower in the zinc group (P < 0.01 and P = 0.01, respectively). Zinc had no effect on C[D.sup.4], CD[8.sup.+], or CD[3.sup.+] cell counts during the follow-up period.

Because of the lack of beneficial effects of zinc on adverse pregnancy outcome and the likelihood of negative effects on hemoglobin concentrations, no compelling evidence exists to support the addition of zinc to prenatal supplements intended for pregnant HIV-infected women.

W. Fawzi, E. Villamor, G. Msamanga, et al. Trial of zinc supplements in relation to pregnancy outcome, hematologic indicators, and T cell counts among HIV-1-infected women in Tanzania. Am J Clin Nutr; 81:161-167 (January, 2005). (Correspondence: WW Fawzi, Department of Nutrition, Harvard School of Public Health, 665 Huntignton Avenue, Boston, MA 02115. E-mail: mina@hsph.harvard.edu).