Maternal and Cord-Blood Thyroid Hormone Levels and Exposure to Polybrominated Diphenyl Ethers and Polychlorinated Biphenyls During Early Pregnancy

• Published in: American journal of epidemiology 2013-09, Vol.178 (5), p.701-713
• Main Authors: ABDELOUAHAB, Nadia, LANGLOIS, Marie-France, LAVOIE, Laetiscia, CORBIN, François, PASQUIER, Jean-Charles, TAKSER, Larissa
• Format: Article
• Language: English
• Subjects: Adolescent; Adult; Biological and medical sciences; Confounding Factors (Epidemiology); Environmental Pollutants - blood; Epidemiology; Female; Fetal Blood - chemistry; General aspects; Halogenated Diphenyl Ethers - blood; Health Behavior; Human exposure; Humans; Lipids - blood; Maternal Exposure; Medical sciences; Miscellaneous; PCB; Polychlorinated biphenyls; Polychlorinated Biphenyls - blood; Pregnancy; Pregnancy Trimester, First - blood; Prospective Studies; Public health. Hygiene; Public health. Hygiene-occupational medicine; Quebec; Socioeconomic Factors; Thyroid diseases; Thyroid Gland - metabolism; Thyroid Hormones - blood; Thyrotropin - blood; Thyroxine - blood; Triiodothyronine - blood; Young Adult
• ISSN: 0002-9262; 1476-6256
• DOI: 10.1093/aje/kwt141

Thyroid hormones play a critical role in the growth of many organs, especially the brain. Polybrominated diphenyl ethers (PBDEs) and polychlorinated biphenyls (PCBs) interact with the thyroid pathway and may disturb neurodevelopment. This prospective study was designed to examine associations between maternal blood PBDEs and PCBs in early pregnancy and levels of thyroid hormones in maternal and umbilical-cord blood. Levels of low-brominated PBDEs, 3 PCB congeners, total and free thyroid hormones (triiodothyronine (T3) and thyroxine (T4)), thyroid-stimulating hormone, thyroid peroxidase antibodies, iodine, selenium, and mercury were measured in 380 pregnant women in the first trimester who were recruited at the University Hospital Center of Sherbrooke (Quebec, Canada) between September 2007 and December 2008. Thyroid hormone levels were also assessed at delivery and in cord blood (n = 260). Data were analyzed on both a volume basis and a lipid basis. At less than 20 weeks of pregnancy, no relationship was statistically significant in volume-based analysis. In lipid-based models, an inverse association between maternal PBDEs and total T3 and total T4 and a direct association with free T3 and free T4 were observed. At delivery, in both analyses, we observed negative associations between maternal total T4, free T3, cord-blood free T4, and PBDEs and between maternal free T3 and PCBs. Our results suggest that exposure to PBDEs and PCBs in pregnancy may interfere with thyroid hormone levels.