A study finds that atmospheric pollution experienced during pregnancy can have an impact on the growth of a newborn baby
The impact of air pollution is one that has become starkly highlighted across cultures and societies in every country, since the beginning of the COVID pandemic.
People who lived in areas highly exposed to pollutants found that they were more likely to contract the virus, which further impacts the capacity to breathe. Sometimes, the likelihood of exposure falls disproportionately on those who are socially disadvantaged.
Speaking to us about her work unconnected to this study, Elica M Moss from Alabama A&M University said: “African Americans, people of colour and those from low-income communities face many environmental issues in addition to air pollution exposure. One of great concern is the proximity to hazardous waste facilities and landfills often located in communities of colour which in addition to leading to disproportionate exposures to air pollutants, similarly, results in matters related to soil and water quality.”
In a separate study, researchers examined the impact of air pollution on childhood asthma.
In another, the research team made a connection between childhood air pollution exposure and future intelligence, which found that a cognitive decline was more likely if a child lived in a more polluted atmosphere.
Thyroid hormones are essential for regulating foetal growth and metabolism, and play an important role in neurological development. Thyroxine is the main thyroid hormone that is circulating and the thyroid-stimulating hormone is TSH. At 48 hours newborn babies undergo a heel prick test in which thyroxine and TSH levels in the blood are measured. In fact, if the balance of these thyroid hormones is not right, the risk of developing serious diseases increases.
So, could air pollution actually shape the growth of the newborn baby?
‘Exposure during the first months has direct influence’ says researcher
Amaia Irizar-Loibide, a researcher in the UPV/EHU’s Department of Preventive Medicine and Public Health, said: “The results obtained in this study have revealed the direct relationship between exposure to fine particles during pregnancy and the level of thyroxine in newborns. However, we have not observed a clear link with exposure to nitrogen dioxide.
“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.”
Researchers want to understand if air pollution has more impacts
Amaia Irizar-Loibide further commented: “The next task would be to study the mechanisms by which these fine particles cause opposing effects in early and late pregnancy. In fact, these particles are nothing more than small spheres made up of carbon, and it is not clear whether the effect these spheres exert is because they pass from the placenta to the baby, whether other components attached to the particles are released once they have entered the body.
“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.”