Exposure to air pollution during the first three months of pregnancy is associated with lower language abilities in toddlers, while preterm infants appear particularly vulnerable to pollution’s impact on motor development, according to a new study.
Researchers, led by King’s College London, studied 498 mother-child pairs from Greater London, using modelled air pollution data based on maternal postcodes during pregnancy. Child development was assessed between 17 and 34 months of age using the Bayley Scales of Infant and Toddler Development.
Lead author Dr Alexandra Bonthrone, School of Biomedical Engineering & Imaging Sciences, at King’s College London, said: ‘We wanted to establish if air pollution levels related to cognitive, language and motor abilities in this critical period of early childhood.
‘The first 1,000 days from conception to age two shape long-term brain health and behaviour.’
The findings show that higher exposure to PM2.5, PM10 NO2 in the first trimester was linked to lower language composite scores at 18 months. The effects remained significant after adjusting for factors including socioeconomic status, ethnicity, birth weight, pregnancy complications, and whether a parent spoke English as an additional language.
Children in the highest pollution exposure group scored on average 5 to 7 points lower in language assessments than those in the lowest exposure group.
The study identified the first trimester as the most critical window for language development, suggesting that air pollution may alter neurogenesis when core language networks are first forming in the developing brain.
The research also found that gestational age at birth significantly changed the relationship between pollution and motor skills. Higher pollutant exposure across the whole of pregnancy was associated with lower motor scores in toddlers born before 32 weeks, but not in those born at or after 32 weeks.
Among the most premature infants, those with the highest pollution exposure scored 11 points lower on motor assessments than those with the lowest exposure.
These associations remained significant even after adjusting for neonatal intensive care factors such as length of hospital stay, respiratory support, and parenteral nutrition.
Dr Bonthrone added: ‘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 into education and information processing, but we won’t know for sure until we do future studies.’
While the effects observed were small, researchers note that air pollution is a near-universal exposure affecting billions of people worldwide. They call for further research into the biological mechanisms linking pollution to altered brain development, including placental changes, inflammation, and oxidative stress.
Professor Stephen Holgate, Principial Investigator of MRC and National Institute for Health and Care Research Net Zero Health Research Network, said: ‘Prenatal exposure to air pollution directly impacts foetal development and setting the stage for lifelong health issues.
‘While we’ve known about the respiratory and birth weight risks for a while, the shift toward neurodevelopment is revealing.
‘This key study adds to the growing body of evidence uncovering just how vulnerable the developing brain is to environmental toxins.
‘However, in taking account of only outdoor air pollution exposure, these findings are likely to underestimate pollution effects since pregnant mothers spend over 70% of their time indoors, where most of their exposure to air pollution will occur.
‘Indeed, the indoor environment is the new frontier for pursing early life health effects of air pollution.’
The full research can be read here.
Photo: Stephen Andrews
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