Exposure to air pollution during pregnancy affects thyroid hormones essential to regular foetal growth and metabolism, researchers at the University of Basque Country have discovered.
In a recent study, researchers studied the link between nitrogen dioxide and particulate matter exposure, and the thyroid hormone thyroxine.
Thyroxine is the primary thyroid hormone, its primary function is to regulate foetal growth and metabolism, but it is also paramount in neurological development.
The study, published in the Journal of Environmental Research, discovered that there is a direct link between particulate matter exposure during pregnancy and thyroxine levels in newborns. Yet there was less of a link with nitrogen dioxide exposure.
Lead author of the study, Amaia Irizar-Loibide, commented: ‘What we have seen in this work, is that exposure during the first months of pregnancy has a direct influence on the balance of thyroid hormones.
‘These babies tend to have a lower level of thyroxine. As the pregnancy progresses, we found that this relationship gradually diminishes, i.e. the mother’s exposure gradually becomes less important. In late pregnancy, however, this link becomes apparent again but displays an opposite effect: as the concentration of these fine particles increases, we have seen that the level of thyroid hormones also increases, which has the opposite effect on the balance.
‘It is not clear what mechanism lies behind all this. In any case, we have come to the conclusion that the most sensitive periods of pregnancy in terms of atmospheric pollution are the early and late months.
‘We need to continue to investigate whether exposure during pregnancy affects not only thyroid hormones, but also other aspects such as neuropsychological development, growth, obesity.’
Nitrogen dioxide and fine particulate matter are the two main pollutants released by road traffic. In particular, particulate matter has been found to enter the bloodstream and infiltrate every organ in the body.
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