Changes in maternal serum chlorinated pesticide concentrations across critical windows of human reproduction and development.

Investigators often employ a single cross-sectional measure of in utero exposure when evaluating associations between organochlorine (OCs) pesticides/metabolites and adverse reproductive outcomes. Few data are available on the stability of exposures to OCs over critical windows of human reproduction and development inclusive of the periconception window. Our objective was to measures changes in OC concentrations prior to conception and throughout pregnancy or after 12 unsuccessful months attempting pregnancy. Seventy-nine women planning pregnancy were prospectively enrolled and followed for up to 12 menstrual cycles. Blood specimens were obtained for toxicologic analysis of seven OCs from participating women at baseline (preconception, n=79), at the first prenatal visit following a positive pregnancy test leading to a live birth (n=54) or after pregnancy loss (n=10), at approximately 6 weeks post-partum (n=53), and after 12 unsuccessful cycles (n=9). Overall and daily rate of change in OCs concentration (ng/gserum) were estimated adjusting for serum lipids and baseline concentration. Significant (P<0.05) decreases in the overall and daily rate of change in OCs concentrations (ng/mLserum) were observed from baseline to pregnancy for HCB (-0.032, -0.001, respectively) and trans-nonachlor (-0.050, -0.002, respectively) while oxychlordane demonstrated an increase during this critical window (0.029, 0.001, respectively). Significant decreases in aldrin (-0.002, -1.47x10(-4), respectively), HCB (-0.069, -0.003, respectively), and trans-nonachlor (-0.045, -0.002, respectively), and an overall increase for oxychlordane (0.015) were seen for women with pregnancy losses. Significant decreases also were observed among infertile women for aldrin (-0.003, -3.52x10(-6), respectively), DDE (-0.210, -4.29x10(-4), respectively), and HCB (-0.096, -2.03x10(-4), respectively), along with an increase for trans-nonachlor (0.034, 7.59x10(-5), respectively). These data, though limited by sample size and the possibility of laboratory measurement error, suggest that OC concentrations may change over critical windows. This underscores the importance of timing biospecimen collection to critical windows for development in the assessment of reproductive and/or developmental effects.