Controlled trial of zinc supplementation in Chilean pregnant adolescents

Objective. The aim of this study was to analyze the effect of zinc supplementation on pregnancy outcome of Chilean adolescents from low socio-economic status (LSES); they often have low zinc intakes which may affect normal growth. Study design. A double blind randomised zinc supplementation trial was conducted with 804 healthy pregnant adolescents of LSES (age 16 +/- 1.3 y.). Individuals were randomly assigned to Zn supplemented (S, n = 401) or Placebo (P, n = 403) groups. During the follow-up 297 were excluded. The S group received 20 mg Zn/d and the P group received a placebo, starting before 20 weeks of gestation. Results. On admission, both groups were comparable in age, rate of underweight, gestational age (12.5 vs 12.8 weeks), and dietary zinc intakes (7.3 vs 7.6 mg/d). At delivery, the S group presented a birthweight of 3,319 +/- 460 g compared with 3,250 +/- 514 g in the P group (NS). The proportion of low birthweight (<2,500 g) in the S group was significantly lower than in the P group (6/249 vs 16/258, p = 0.036). Prematurity rate was lower in S than P (14/249 vs 30/258, p = 0.016). Multiple regressions found a significant effect of maternal nutritional status (p = 0.011) and zinc supplementation (p = 0.05) on birthweight, No effects on pregnancy complications, RBC or plasma alkaline phosphatase were found. Conclusions. Oral zinc supplementation affects favourably the pregnancy outcomes in Chilean adolescents from low socioeconomic status. (C) 2001 Elsevier Science Inc. All rights reserved.