Thyroid stimulating hormone levels in newborns and early life exposure to endocrine disrupting chemicals: analysis of three European mother-child cohorts

BACKGROUND: Various studies report interactions between thyroid hormones and early life chemical exposure. Our objective was to analyse associations between markers of endocrine disrupting chemical exposure and thyroid function in newborns, determined in heel prick blood spots.

METHODS: Three European mother-child cohorts (FLEHSI - Belgium, HUMIS - Norway, and the PCB cohort - Slovakia. Total n=1784) were pooled for the purpose of this study. Data on Thyroid Stimulating Hormone (TSH) was obtained from national neonatal screening registries, and cord plasma and/or breast milk was collected to determine exposure to various chemicals. Multiple regression models were composed with exposure and cohort as fixed factors, and adjustments were made for a priori defined covariates.

RESULTS: Median TSH concentrations were 1.00, 1.10, and 2.76 mU/l, for the Belgian, Norwegian, and the Slovak cohort, respectively. For polychlorinated biphenyl (PCB)-153 and dichlorodiphenyldichloroethylene (p,p'-DDE), children in the third exposure quartiles had a 12 - 15% lower TSH at birth. Results remained unchanged after additional adjustment for birth weight and gestational weight gain. No effect on TSH was observed for the other compounds.

CONCLUSION: Early life exposure to PCB-153, and p,p'-DDE was associated with newborn TSH levels. Higher exposure levels were associated with 12-15% lower TSH levels.