A new study by researchers at King’s College in London has found that babies exposed to high levels of air pollution in the womb showed slower developmental progress at 18 months than those who faced lower levels.
The research, which was described by King’s College as the first of its kind in London, examined the language and motor development of infants whose mothers were pregnant in Greater London.
In all, 498 infants from St Thomas’ Hospital between 2015 and 2020 were monitored in the study, with 125 of them born prematurely, of which 54 were described as very or extremely preterm.
According to the study, exposure to air pollution produced by fumes from cars in traffic during the first trimester of pregnancy, which is described as the period from conception to about 12 or 13 weeks, was linked to poorer language performance in toddlers at 18 months.
While preterm babies are already more likely to have difficulties with motor development, we adjusted for different clinical factors, like time spent on support for breathing, to confirm the relationship between air pollution and motor development.
Researchers also found that babies born prematurely appeared to be more vulnerable to the effects of pollution exposure while their mothers were pregnant.
“While preterm babies are already more likely to have difficulties with motor development, we adjusted for different clinical factors, like time spent on support for breathing, to confirm the relationship between air pollution and motor development,” Dr. Alexandra Bonthrone, from the School of Biomedical Engineering & Imaging Sciences, at King’s College London, who led the research, said.
The study showed that preterm infants exposed to higher pollution levels were worse off when they were tested, in not only in language development but also in motor skills.
The children assessed also underwent developmental assessments using the Bayley Scales, a standard clinical test that measures cognitive, language, and motor abilities.
According to the findings, babies exposed to higher pollution levels during the first trimester scored, on average, between five and seven points lower on the language tests than those exposed to lower levels.
There was, however, no significant link found between pollution exposure during the second and third trimesters and developmental outcomes.
Of the babies born prematurely, those exposed to the highest pollution levels throughout pregnancy scored about 11 points lower on motor development tests than infants exposed to lower pollution levels.
The researchers worked with Imperial College London using the London Air Pollution Toolkit, which calculates pollution levels based on traffic volume and average vehicle speeds, to measure the levels of pollution
This allowed the research team to estimate maternal exposure to pollutants such as particulate matter and nitrogen dioxide.
According to Dr. Bonthrone, the first 1,000 days of life, from conception to the age of two, are critical for a child’s long-term brain health and behaviour.
“At this stage, it is too early to say whether these babies will catch up with their peers. The only way will be to study them later in childhood. It could be that the development differences have effects on education and information processing, but we won’t know for sure until we do future studies,” she added.
Senior author Serena Counsell, of the School of Biomedical Engineering & Imaging Sciences, King’s College London, said the findings were worrying and indicated that even indirect exposure to air pollution through their mothers could affect children’s development.
“This work adds to a growing body of evidence that maternal exposure to high levels of air traffic pollution may be associated with altered outcomes in their offspring. Reducing maternal exposure to air traffic pollution should be a public health priority,” she said.
Professor Frank Kelly, from the Environmental Research Group at Imperial College London, who is also Deputy Director for MRC Centre for Environment and Health, noted that even within the WHO’s legal air quality limits, pregnant women and children were still being adversely affected.
This study shows that even within what we currently call ‘legal’ levels of air pollution, we are seeing measurable impacts on the developing brain. That should fundamentally change how we think about ‘acceptable’ air quality for pregnant women and young children. Improving air quality is not just about cleaner skies; it is about giving every child the best possible start in life.
The study, which was published in the Journal of Physiology, forms part of wider research following a cohort of children who underwent brain MRIs before or soon after birth, known as the Developing Human Connectome Project.
This study was supported by the UKRI Medical Research Council (MRC) UK, the European Research Council under the European Union’s Seventh Framework Program, the Wellcome/EPSRC Centre for Medical Engineering and a King’s Together Award.
This story was a collaboration with New Narratives. Funding was provided by the Clean Air Fund which had no say in the story’s content.
