Exposure to air pollution during pregnancy may affect the development of thyroid hormones which are essential for regulating foetal growth and metabolism, according to researchers at the University of the Basque Country
In the study, which was published in the journal Environmental Research, the researchers looked at the connection between exposure to nitrogen dioxide (NO2) and particulate matter (PM2.5) and thyroxine (T4).
T4 is the main thyroid hormone, this hormone is essential for regulating foetal growth and metabolism and it also plays an important role in neurological development.
If the balance of the thyroid hormones are not right, the risk of developing serious diseases increases.
The researchers found that there is a direct relationship between exposure to PM2.5 during pregnancy and the level of thyroxine in newborns.
However, there was less of a clear link with exposure to NO2.
Amaia Irizar-Loibide, lead author of the study said: ‘These results coincide with the limited previous research. 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, etc.’
In related news, birth rates are decreasing worldwide, and in European countries, they are even dropping below population replacement levels. While these decreases might be due to many adults postponing having children, an increasing body of research suggests that this is not the full picture. Air Quality News investigates the worrying environmental factors that may be responsible for our declining fertility rates.Photo credit – freestocks