Prenatal exposure to air pollution during the early and middle stages of pregnancy is associated with adverse neurodevelopmental outcomes at ages 1 to 3 years.

Background: A large body of data shows that fetal brain development is vulnerable to disruption by air pollution experienced by the mother during pregnancy, adversely affecting cognitive and psychomotor capabilities during childhood (De Asis-Cruz et al., Biol Psychiatry 7:480-90, 2022; Morgan ZEM et al., Environ Health 22:11, 2023). This study has sought to identify gestational windows of susceptibility to prenatal exposure to air pollution.

Methods: 470 African American and Latina mother/child pairs participated in a prospective cohort study based in the low-income communities of Northern Manhattan and the South Bronx, New York City. Gestational exposure to respirable particulate matter (PM_2.5) and nitrogen dioxide (NO₂) was assessed through validated models in relation to cognitive and motor development assessed at ages 1, 2, and 3 years using the Bayley-II Scales. Multiple linear regression models and distributed lag models (DLM) were used to identify critical windows of exposure by trimester and week of pregnancy.

Results: By linear regression, average exposures to NO₂ during the first and second trimesters and the entire pregnancy were significantly and negatively associated with the mental developmental index (MDI) at age 1. Average exposures to PM_2.5 during the second trimester and the entire pregnancy were also significantly, inversely associated with age 1 MDI. No significant associations were found between these exposures and MDI at age 2. NO₂ exposure during the first trimester was significantly negatively associated with MDI at age 3. Using DLM, exposures to NO₂ at lags 29-30 weeks (within the first trimester) and PM_2.5 at lags 17-18 weeks (second trimester) were significantly and inversely associated with MDI at age 1. Significant, inverse associations were found between exposures to NO₂ at lag 29 weeks and PM_2.5 at lags 27-29 weeks and children's MDI at age 3. No significant associations were found between psychomotor index (PDI) and prenatal exposures to NO₂ or PM_2.5 at ages 1, 2 or 3.

Conclusions: Our finding that prenatal exposure to air pollution in the first and second trimesters was associated with lower scores for cognitive development at ages 1 and 3 is of concern because of the potential consequences of these outcomes for long-term functioning. They underscore the need for stronger policies to protect pregnant individuals and offspring, particularly during vulnerable, early life-stage of development.