Effects of pregnancy on the inter-individual variations in blood levels of lead, cadmium and mercury.

Blood samples to be analysed for lead, cadmium and mercury were taken from 417 pregnant women not occupationally exposed to these metals. Each subject was paired with a non-pregnant woman of the same age (+/- 2 years), socio-economic status, alcohol and tobacco status. Most of the inter-individual variations observed in earlier studies were confirmed in the control group. Among the pregnant women, however, such variations in blood metal levels appeared to be somewhat different compared to the control women according to the parameters studied: age of the women, alcohol and tobacco consumption. Furthermore, the study of the evolution of blood levels of lead, cadmium and mercury throughout pregnancy revealed a significant decrease in cadmium levels during the first half of pregnancy. A similar tendency was observed for lead but this did not attain statistical significance.