Problem. Zinc deficiency affects one-third of the world's population and has gained notoriety for its associations with global disease burden and growth faltering. The objective of this thesis was to evaluate the effects of zinc supplementation during pregnancy on the growth, body composition, and morbidity outcomes of infant offspring.
Methods. From 1995–1997, a double-blind, randomized controlled trial of prenatal zinc supplementation was conducted in Villa El Salvador, Peru. Pregnant women were randomized to receive either zinc (15 mg Zn + 60 mg Fe + 250 μg folic acid) or placebo (60 mg Fe + 250 μg folic acid) daily through one month post-partum. Of the 579 newborns enrolled for the follow-up phase, samples were drawn for the characterization of growth and body composition (n=232) and the assessment of zinc effect on growth (n=550) and morbidity (n=421) outcomes. Monthly anthropometric measures were collected through 12 mo, and weekly morbidity and dietary intake surveillance was undertaken from 6-12 mo.
Results. The linear and somatic growth of the Peruvian infants were similar to trajectories from the WHO International Growth Standards (2006); prevalences of stunting, undernutrition, and wasting were low (<4%). Prenatal zinc supplementation demonstrated significant increases in weight (P=0.007), calf circumference (P<0.001), and chest circumference (P=0.016) adjusting for covariates. No effects on linear growth or skinfold indicators of adiposity were observed. Infants whose mothers were supplemented with zinc showed a reduced risk for severe diarrhea [OR 0.55, 95%CI 0.40–0.74, P<0.001], mucus in the stools [OR 0.53, 95%CI 0.48–0.57, P<0.001], diarrheal episodes lasting longer than one week [OR 0.65, 95%CI 0.43–0.98, P=0.04], impetigo [OR 0.07, 95%CI 0.01–0.81, P=0.03], and acariasis (scabies) [OR 0.14, 95%CI 0.03–0.73, P=0.007] compared to the control group. No treatment effect on respiratory illnesses or time to first diarrheal episode were found.
Conclusion. Prenatal zinc supplementation in this at-risk population showed positive growth and morbidity outcomes in the infants. Additional studies are recommended to corroborate these findings and to further distinguish short-term metabolic vs. long-term genetic alterations induced by zinc during pregnancy.