Exposure to fine particulate matter (PM2.5)—very small inhalable particles found in air pollution—during early pregnancy was associated with babies being slightly smaller at birth, according to a new ECHO Cohort study led by Daniel Enquobahrie, PhD, MD, MPH of the University of Washington School of Public Health and Adaeze Wosu Nzegwu, PhD, MPH of Johns Hopkins Bloomberg School of Public Health.
Exposure to PM2.5 is widespread and linked to various health risks, including respiratory, cardiovascular, and metabolic diseases. Previous research has examined the effects of PM2.5 exposure during pregnancy on birth outcomes, but gaps remain. More research is needed to understand whether there are critical windows during pregnancy when PM2.5 exposure is most impactful. For this study, researchers used information from 19,108 mothers and their babies from 51 ECHO Cohort Study Sites across the United States to evaluate how timing of PM2.5 exposure affects birth outcomes. They also explored whether associations differ by infant sex and maternal race and ethnicity.
Key Takeaways include:
- Exposure to higher levels of PM2.5 during the first weeks of pregnancy was linked to babies being slightly smaller at birth and having a higher chance of being born small for their gestational age (smaller than average for the length of pregnancy).
- There was no significant association between PM2.5 exposure and shorter pregnancies or preterm birth.
- For baby girls, higher PM2.5 exposure in early pregnancy seemed to affect their birth size more than for baby boys, suggesting that the baby's sex can make a difference in how air pollution affects growth.
- The effects of PM2.5 on birth outcomes like being born prematurely, birth size, or being small for gestational age varied depending on the mother's race and ethnicity.
“This study on PM2.5 exposure during pregnancy and birth outcomes can inform ongoing discussions on regulations that impact PM2.5 exposure, such as traffic-related air pollution.” said Dr. Enquobahrie.
Further research could help investigators better understand the mechanisms underlying differences in air pollution vulnerability by infant sex, and by maternal race and ethnicity. Additional studies could also help researchers understand how other factors, such as diet and lifestyle, influence the relationship between PM2.5 exposure and birth outcomes.
This collaborative research, titled “Gestational fine particulate matter exposure and perinatal outcomes in the ECHO cohort: Associations across pregnancy windows,” is published in Environmental Research.