Relationship between maternal serum zinc, cord blood zinc and birth weight of term newborn infants in Jos, Plateau State, Nigeria
Background: Adequate in utero supply of zinc is essential for optimal fetal growth because of the role of zinc in cellular division, growth and differentiation. Low maternal serum zinc has been reported to be associated with low birth weight and the later is associated with increased morbidity and mortality in newborns. In Nigeria, where the prevalence rates of zinc deficiency among pregnant women, low birth weight and infant mortality are high; it will be useful to determine the relationship between maternal and cord serum zinc levels and birth weight.
Methods: Across-sectional study of 190 mothers and their term babies. Blood samples were collected from the mothers and cord of the babies immediately after delivery for serum zinc analysis using atomic absorption spectrophotometry. Babies' weights were measured within thirty minutes post-delivery.
Results: The mean age of the mothers and gestational age of the babies were 28.29 ± 5.64 years and 39.2 ± 1.2 weeks respectively. The mean birth weight of the babies was 3106.7 ± 411.2 g; while the mean maternal and cord serum zinc concentrations were 48.5 ± 17.6 μg/dl and 99.3 ± 21.5 μg/dl respectively. There was no association between the maternal serum zinc and cord serum zinc (p = 0.62); and likewise maternal serum zinc and birth weight (p =0.99). However, there was a significant positive association between cord serum zinc and birth weight (p < 0.001, r = 0.02, p= 0.04).
Conclusion: The study outcome suggests that cord serum zinc but not maternal serum zinc predicts birth weight. In spite of low maternal serum zinc level, an adequate amount of zinc could be transferred to the babies thereby preventing zinc deficiency in the babies and aiding their growth. More studies are needed on the mechanism of placental zinc transfer.
Keywords: Maternal zinc, cord zinc, birth weight, Jos, Nigeria