A new international study indicates that prenatal exposure to common urban air pollutants could subtly influence fetal brain development during key stages of pregnancy. Published in The Lancet Planetary Health, the research urges stronger public health measures to reduce pollution exposure for pregnant people, with relevance for densely populated cities like Bangkok. Data from the Barcelona Life Study Cohort (BiSC) informed the findings, which examined pollutants such as NO₂, PM2.5, and black carbon using advanced ultrasound imaging in more than 750 mother–fetus pairs.
The study, led by the Barcelona Institute for Global Health (ISGlobal) in collaboration with major university hospitals, provides the most detailed picture to date of how these pollutants relate to brain structure. The team tracked changes in brain morphology during the second and third trimesters, a critical window for neural development, by analyzing ultrasound scans throughout late pregnancy. In Thailand, where air quality often dominates health headlines, the implications of these results are especially timely as Bangkok and Chiang Mai report periodic spikes in particulate matter.
Researchers found that higher exposure to NO₂, PM2.5, and black carbon was associated with subtle increases in several brain cavities, including the lateral ventricles and the cisterna magna, spaces filled with cerebrospinal fluid. There was also enlargement of the cerebellar vermis, a region involved in motor control. Black carbon exposure correlated with a shallower Sylvian fissure, a feature linked to maturation and sensory processing. Importantly, all observed brain size changes remained within normal ranges at birth.
Experts emphasize that while individual changes may be small, widespread exposure could have meaningful population-level effects on child development. “During mid to late gestation, the fetal brain is especially vulnerable to external factors like pollution,” said a senior ISGlobal investigator involved in the study. Clinicians from Barcelona’s maternity hospitals stressed that even pregnancies appearing healthy can be subtly affected by air pollution.
In Bangkok’s context, Thai public health professionals note that pollutant levels during peak seasons can rival those studied in Europe. This strengthens the case for urban and environmental policy actions to protect expectant mothers and their babies. Although none of the newborns in the study showed overt abnormalities, researchers warn that subtle brain differences may signal longer-term developmental risks and should be pursued in follow-up studies.
The study uses geolocation data to estimate exposure across three microenvironments—home, work, and commuting routes—paired with third-trimester ultrasound data to link pollutant concentrations with brain structure. While the results are not a diagnosis, they contribute to understanding how prenatal environments influence neurodevelopment and highlight the need for protective interventions.
Public health authorities in Thailand, including the Ministry of Public Health, have made strides to curb air pollution, such as seasonal restrictions on outdoor burning and stricter vehicle-emission controls. However, many urban residents remain unaware of prenatal risks. In private clinics, air purifiers and high-grade masks have become common recommendations during haze periods, though access remains uneven.
Thai researchers have long documented PM2.5’s effects on respiratory and birth outcomes; this study adds a direct link to fetal brain development, potentially guiding new research funding and collaborations within the Kingdom. Globally, the World Health Organization notes that most children are born into environments with unhealthy air, underscoring the value of preventive measures before birth. A multi-country analysis in 2023 linked PM2.5 increases with higher risks of preterm birth and low birth weight—factors associated with neurodevelopmental challenges.
Thailand’s aging birth rate means each birth carries growing social and economic significance. Reducing invisible risk factors during pregnancy could help protect future generations and the country’s workforce. The authors call for a multi-layered approach: stricter vehicle and industrial emissions, expansion of green and blue infrastructure to lower urban pollution, and broader public education for healthcare providers and expectant families.
Practical steps for Thai readers include:
- Limit outdoor activity on high-pollution days and monitor PM2.5 in real time via reliable local apps.
- Improve indoor air quality with ventilation and, where possible, HEPA-filter air purifiers.
- Avoid open burning, construction sites, and heavy traffic areas when feasible.
- Discuss protective strategies with healthcare professionals, especially during the second and third trimesters.
- Support community efforts advocating for cleaner air policies and enforcement.
As urbanization continues, safeguarding the developing brain begins in the womb. This study provides evidence that the air pregnant people breathe could influence the minds of tomorrow’s Thai youth. Ongoing monitoring of science and policy will be essential to translate these findings into healthier outcomes.
For ongoing updates on air quality and maternal health, readers can follow credible health and science coverage from Thai public health authorities and major health institutions.