Blood lead and cadmium and birth weight among sub‐arctic and arctic populations of Norway and Russia

Abstract

Delivering women and their newborns in the Kola Peninsula of Russia and the neighboring arctic area of Norway were studied to explore relationships between maternal cadmium and lead status and birth weight as a pregnancy outcome. Life-style information, maternal blood and cord blood specimens were collected from 50 consecutive mother-infant pairs from hospital delivery departments in three Russian and three Norwegian communities. Pregnancy outcomes were verified by consulting medical records. Lead and cadmium were determined in the blood samples by electrothermal atomic absorption spectrometry. The median blood-cadmium concentration for the Russian mothers was 2.2 nmol/L (n = 148) versus 1.8 nmol/L in the Norwegian group (n = 114, p = 0.55). A weak association was observed between maternal cadmium and amount smoked (r = 0.30, p<0.001); no correlation was found between maternal blood cadmium and birth weight. The corresponding maternal lead values were 0.14 (Russia) and 0.06 micromol/L (Norway), p<0.001. The latter lead concentration constitutes one of the lowest adult population values reported to date. Maternal and cord blood lead levels were strongly correlated (r = 0.88, p<0.001). In a multivariate linear regression model, maternal blood lead was recognized as a negative explanatory variable (p<0.05) for birth weight and child's body mass index (BMIC), with or without adjustment for gestational age. A similar association was suggested by ANOVA-analysis of maternal blood lead by quartiles. Maternal blood-lead level as an environmental factor is an apparent predictor of low birth weight and BMIC. It reduced substantially the contribution of a country factor in explaining the observed differences in birth weight.