Maternal zinc supplementation does not affect size at birth or pregnancy duration in Peru

To estimate the effect of maternal zinc deficiency on pregnancy outcomes, w e conducted a zinc supplementation trial in an urban shantytown in Lima, Pe ru, a population with habitual low zinc intakes. Beginning at 10-24 wk gest ation, 1295 mothers were randomly assigned to receive prenatal supplements containing 60 mg iron and 250 (g folate, with or without 15 mg zinc. Women were followed up monthly during pregnancy. At birth, newborn weight was rec orded, and crownheel length, head circumference and other circumferences an d skinfold thicknesses were assessed on d 1. At delivery, 1016 remained in the study; duration of pregnancy was known for all women, and birth weight information was available for 957 newborns. No differences were noted in du ration of pregnancy (39.4 +/- 2.2 vs. 39.5 +/- 2.0 wk) or birth weight (326 7 +/- 461 vs. 3300 +/- 498 g) by prenatal supplement type (iron + folate zinc vs. iron + folate; P > 0.05), and there were no differences in the rat es of preterm (<37 wk) or post-term (>42 wk) delivery, low birth weight (<2 500 g) or high birth weight (>4000 g). Finally, there were no differences b y prenatal supplement type in newborn head circumference, crownheel length, chest circumference, mid-upper arm circumference, calf circumference or sk infold thickness at any of three sites. Adjustment for covariates and confo unding factors did not alter these results. Adding zinc to prenatal iron an d folate tablets did not affect duration of pregnancy or size at birth in t his population.