CEREBRAL palsy (CP) is the leading cause of physical disability in children, and air pollutant exposure during pregnancy could increase the risk of its development in infants. Previous studies have proved that air pollution, particularly fine particulate matter (PM2.5), defined by a diameter ≤2.5 μm, can alter brain structure and lead to cognitive development delays. A recent study, conducted by Yu Zhang, Chan School of Public Health, Harvard, Boston, Massachusetts, USA, and colleagues, investigated the link between ambient air pollution during pregnancy and CP risk among full-term births.
This study utilised population-based data from Ontario, Canada. Weekly average concentrations of PM2.5, nitrogen dioxide, and ozone measurements were collected during pregnancy. Data were selected for use in the study from 1,587,935 mother–child pairs of singleton full-term births born between 1 April 2002–31 March 2017. Of the monitored cohort, 0.2% of the children were diagnosed with CP. A CP diagnosis was based on either an inpatient hospitalisation diagnosis or two or more outpatient diagnoses within 2 weeks. Follow-ups continued from birth until the study’s end, death, or relocation outside Ontario, whichever occurred first.
The study discovered that prenatal exposure to air pollution, particularly PM2.5, increased the risk of cerebral palsy in full-term infants. The study also examined differences in cerebral palsy risk based on the infant’s sex and found the risk was slightly higher for male infants compared to female infants, although this difference was not statistically significant. The first two trimesters of pregnancy were identified as particularly critical periods for exposure to PM2.5, potentially impacting the infant’s neuronal development.
Possible mechanisms of development were discussed including increased air pollutant exposure during fetal brain development; air pollution causing chronic neuroinflammation; epigenetics DNA methylation, which has been hypothesised to be a mechanism for CP; and finally sex differences in inflammation. Going forward, further research is required to validate these results and determine potential modifiers.
Katie Wright, EMJ
Reference
Zhang Y et al. Prenatal exposure to ambient air pollution and cerebral palsy. JAMA Netw Open. 2024;7(7):e2420717.
