A longitudinal assessment of maternal zinc status in normal pregnant women

Abstract

Maternal zinc (zn) status has been extensively studied. Debate continues regarding what should be the anticipated changes in zn indices throughout gestation. The purpose of this study was to assess zn status during pregnancy in a well-defined group of pregnant women. Maternal zn status was assessed serially in 33 healthy, non-smoking women throughout pregnancy at 9, 17, 25, 34 weeks gestation and again at delivery. The concentrations of zn in plasma (pl), red blood cells (rbc), and neutrophils (neut) were quantified by atomic absorption spectrophotometry. Total plasma alkaline phosphatase (alk phos) activity was determined by colorimetric methods. Study subjects were (mean ± SD) age 28.3 ± 5.1 years. The following changes in biochemical indices (mean ± SD) were noted at 9, 17, 25, and 34 weeks gestation, and again at delivery, respectively. Pl zn (micrograms/deciliter (mog/dl)) was 77.5 (± 12.8), 67.5 (± 8.2), 59.5 (± 7.2), 56.8 (± 9.7), and 47.7 (± 12.2). Rbc zn (mcg/dl) was 1105.3 (± 119.8), 1118.8 (± 116.9), 1198.5 (± 108.2), 1267.4 (± 122.5), and 1343.3 (± 125.8). Neut zn (mcg/1010 cells) was 42.4 (± 3.9), 42.4 (± 3.0), 42.5 (± 2.0), 44.5 (± 2.9), and 43.7 (± 3.1). Total plasma alk phos activity (Units/liter) was 3.3 (± 0.7), 3.4 (± 1.0), 3.9 (± 0.8), 6.6 (± 1.9), and 8.7 (± 2.4). The concentrations of zn in pl progressively declined over the course of gestation. The concentrations of zn in rbc and neut, as well as the total plasma alk phos activity progressively increased throughout pregnancy. Significant (p < 0.05) time-dependent changes by analysis of variance with repeated measures (ANOVA) were noted throughout gestation for maternal concentrations of pl zn (p = 0.0001), rbc zn (p = 0.0001), neut zn (p = 0.0091), and total plasma alk phos activity (p = 0.0001). These findings may help formulate standards which may be useful in the assessment of maternal zinc nutriture in the future.