Air Pollution and the Developing Foetal Heart: Investigating Subclinical Cardiac Remodeling in Uterus

The prenatal period is a critical window during which environmental exposures may influence the trajectory of organ development. Among these exposures, ambient air pollution—especially nitrogen dioxide (NO₂), particulate matter (PM₂.₅), and black carbon—has been increasingly associated with adverse birth outcomes. However, its impact on fetal cardiovascular development remains insufficiently explored.

Within the framework of the Barcelona Life Study Cohort (BiSC), our research seeks to address this gap by examining how maternal exposure to air pollution during pregnancy may influence fetal cardiac morphology and function. We employ hybrid models that incorporate machine learning techniques (Random Forest) along with time-activity-adjusted exposure metrics to estimate individualized exposures to NO₂, PM₂.₅, and black carbon across various microenvironments, including the home, workplace, and commuting routes.

These exposure estimates are linked to an extensive set of echocardiographic data obtained in the third trimester (around 32 weeks of gestation). Using standardized fetal cardiosonography protocols, we extract over 70 cardiac parameters, including left and right ventricular and septal wall thickness, myocardial performance index (MPI), E/A ratio, mitral annular plane systolic excursion (MAPSE), and cardiac sphericity index. Together, these parameters provide a detailed assessment of both structural and functional aspects of fetal heart development.

Preliminary analyses suggest that, after adjusting for a range of confounding factors—including gestational age at scan, maternal education, ethnicity, passive and active smoking, alcohol consumption during pregnancy, parity, fetal sex, and household income—higher maternal exposure to air pollutants during pregnancy is associated with subtle yet measurable alterations in cardiac geometry and function. These include increased wall thickness, reduced atrial transverse diameter, and decreased MAPSE, indicating potential early cardiac remodeling. These associations remain robust in a set of sensitivity analyses.

Understanding these early-life cardiovascular alterations is essential, as subclinical deviations in fetal heart development may predispose individuals to long-term cardiovascular vulnerabilities, including hypertension and altered cardiac function in later life. Our findings contribute to the growing body of evidence supporting the need for environmental risk assessment as an integral component of prenatal care, urban design, and maternal-child health policy.

Ongoing work aims to investigate exposure–response relationships across gestational windows, apply advanced statistical techniques (e.g., distributed lag models and outcome-wide analyses), and examine potential effect modification by placental function and hemodynamics.

 

This article was written by Yana Luo, a PhD student on the BiSC Project.