The Relationship between Zinc Concentration of Maternal, Umbilical Cord, and Placenta and Birth Weight

Bai, Hyun Sook; Ahn, Hong Seok

Abstract

The purpose of this study was to assess the maternal zinc status during pregnancy and to evaluate the relationship between the zinc concentration of maternal, umblical cord blood and placental tissue and pregnancy outcomes. Venous blood samples were drawn from 53 pregnant women just before delivery and the cord blood of their newborn babies was collected immediately after birth. In addition, placental tissues were extracted. We investigated the difference in the concentration of zinc in maternal, umbilical cord blood and placental tissue in two gestational age groups (preterm delivery group [PT] and normal term delivery group [NT]) at 34.7 wk and 39.0 wk of mean gestational age, respectively). We also assessed correlations of the zinc concentration of maternal, umbilical cord blood and placental tissue. Lastly, we studied the correlations between the birth weights and the zinc concentration in the maternal, umbilical cord blood and placental tissue. The concentrations of maternal serum zinc and of umbilical cord serum zinc were significantly higher in the PT group (76.9 +/- 37.4 microgram/dl, 101.3 +/- 41.4 microgram/dl) than in those of the NT group (57.8 +/- 22.4 microgram/dl, 80.7 +/- 27.5 microgram/dl), respectively (p < 0.05). The zinc concentration of the umbilical cord blood was significantly higher than that of the maternal blood in both groups (p < 0.05). There was no significant correlation between the gestational age and the serum zinc concentration in the cord or the maternal serum. Our results showed that there was a negative relationship between the birth weight (r = -0.286) and the maternal serum zinc concentration. Despite there not being a significant difference, there was tendency for the highest concentrations of maternal serum zinc to be associated with the lowest birth weights. These findings support a possible relationship between the maternal zinc status and the pregnancy outcome, and suggest that zinc may play a role in the many biological processes involved in the successful outcome of a pregnancy.