Distribution of serum selenium, copper, and zinc in normal human pregnancy.

The distribution of the serum levels of selenium, zinc, and copper in human pregnancy at various gestational ages were determined from two ethnically and geographically different populations (Rosebud Indian Reservation and southeastern South Dakota) of 410 normal subjects. As gestation age increased, there was a significant increase and a slight decrease in the mean levels of copper and zinc, respectively. No change in the levels of selenium was observed. Significantly higher levels of both pregnancy and non-pregnancy serum copper were observed in the Rosebud population compared to that in southeastern South Dakota, possibly due to the significantly higher level of copper in the Rosebud water. No differences were observed in the zinc or selenium levels between the two populations. Serial measurements of these trace metals during the third trimester of pregnancy were performed on 18 subjects, and supported the trends described for copper and selenium. No decrease in zinc was observed in the individual subjects.