Association of Exposure of Pregnant Women to Household Contaminants and Green Space with Cord Blood Thyroid-Stimulating Hormone

Abstract

Background: The association between maternal exposure to pollutants or chemicals and green space and thyroid hormone levels remains inconclusive. There are conflicting results regarding the association of green space and household chemical exposure with thyroid hormone levels in mothers and their fetuses. Objectives: We aimed to evaluate the association between exposure of pregnant mothers to household contaminants and green space and the thyroid-stimulating hormone (TSH) level in cord blood of term newborns. Methods: In this cross-sectional study, 300 pregnant women in the first trimester were enrolled. Data regarding exposure to household chemicals and green space were collected using validated questionnaires administered three times, once in each trimester. The total time of exposure to green space and the total number of exposures to chemicals during pregnancy were calculated. The association between these exposures and cord blood TSH level was investigated. Results: A total of 286 mothers completed the study. The most commonly used pollutants or chemicals by mothers were bleach, glass cleaner, and a traditional natural fume (Esfand). There was no significant association between cord blood TSH level and maternal exposure to pollutants or chemicals and green space. Conclusions: Although exposure to green space and household chemicals may have different health impacts, in the present study, these exposures were not significantly related to neonatal thyroid function. Further longitudinal studies with larger sample sizes and consideration of other confounding factors affecting thyroid hormones are warranted.