Birth Delivery Mode Modifies the Associations between Prenatal Polychlorinated Biphenyl (PCB) and Polybrominated Diphenyl Ether (PBDE) and Neonatal Thyroid Hormone Levels

• Published in: Environmental health perspectives 2008-10, Vol.116 (10), p.1376-1382
• Main Authors: Herbstman, Julie B., Sjödin, Andreas, Apelberg, Benjamin J., Witter, Frank R., Halden, Rolf U., Patterson, Donald G., Panny, Susan R., Needham, Larry L., Goldman, Lynn R.
• Format: Article
• Language: English
• Subjects: Adult; Birth; Blood; Body mass index; Children's Health; Circuit boards; Copyrights; Cord blood; Delivery, Obstetric - methods; Disruption; Environmental Exposure; Environmental health; Ethers; Female; Halogenated diphenyl ethers; Health; Health aspects; Hormones; Hospitals; Humans; Infant, Newborn; Infants; Masks; Maternal Exposure; Measurement; Physiological aspects; Polybrominated biphenyls; Polybrominated Biphenyls - toxicity; Polychlorinated biphenyls; Polychlorinated Biphenyls - toxicity; Pregnancy; Printed circuits; Rope; Serums; Spontaneous; Spots; Statistical significance; Stresses; Thyroid hormones; Thyroid Hormones - blood; Thyroxine
• ISSN: 0091-6765; 1552-9924
• DOI: 10.1289/ehp.11379

Background: Developing infants may be especially sensitive to hormone disruption from chemicals including polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs). Objective: We investigated relationships between cord serum levels of PCBs and PBDEs and thyroid hormones measured in cord blood serum and neonatal blood spots. Methods: We measured PCBs and PBDEs, thyrotropin (TSH), thyroxine (${\rm T}_{4}$) and free${\rm T}_{4}$(${\rm FT}_{4}$) in cord blood serum from 297 infants who were delivered at the Johns Hopkins Hospital in 2004-2005. We abstracted results of total${\rm T}_{4}$(${\rm TT}_{4}$) measured in blood spots collected in the hospital and at neonatal visits. We used delivery mode (augmented vaginal deliveries and nonelective cesarean deliveries) as a surrogate for intrapartum stress, which is known to alter cord blood thyroid hormones. Results: In the full study population, no compounds were associated with a change in average TSH,${\rm FT}_{4}$, or${\rm TT}_{4}$. BDE-100 was associated with increased odds of low cord${\rm TT}_{4}$, BDE-153 with increased odds of low cord${\rm TT}_{4}$and${\rm FT}_{4}$, and no compounds were associated with increased odds of high TSH. For infants born by spontaneous, vaginal, unassisted deliveries, PCBs were associated with lower cord${\rm TT}_{4}$and${\rm FT}_{4}$and lower${\rm TT}_{4}$measured in neonatal blood spots. PBDEs showed consistent but mainly nonsignificant negative associations with${\rm TT}_{4}$and${\rm FT}_{4}$measurements. Conclusions: Prenatal PCB and PBDE exposures were associated with reduced${\rm TT}_{4}$and${\rm FT}_{4}$levels among infants born by spontaneous, unassisted vaginal delivery. Intrapartum stress associated with delivery mode may mask hormonal effects of PCBs and PBDEs.