Serial levels of serum organochlorines during pregnancy and postpartum.

In utero exposure to dichlorodiphenyldichloroethene and polychlorinated biphenyls, within the range found in the general U.S. population, may produce detectable effects in offspring. To design studies of the effects of in utero organochlorine exposure, we obtained data on the relationship between gestational and perinatal maternal levels in females on several occasions. We studied 67 pregnant women in the United States who agreed to have their blood drawn once during each trimester and once postpartum. We examined the Pearson correlation coefficient between the natural logarithm of levels (microg/g serum lipid). The correlation, r, among levels in the first and third trimester was .86 and .77 for dichlorodiphenyldichloroethene and for polychlorinated biphenyls. Correlations among levels determined at other times (i.e., second trimester and postpartum) were similar. On the basis of these results, we suggest that in studies of the effects of in utero or perinatal exposure to the aforementioned compounds, the time when specimens are collected is not critical.