Maternal Exposure to Air Pollution During Early Pregnancy and Congenital Heart Disease: An Exploratory Case-Control Analysis from Delhi NCR.

OBJECTIVES

To investigate the association between periconceptional maternal exposure to air pollution and risk of congenital heart disease (CHD) in the highly polluted Delhi National Capital Region (Delhi-NCR).

METHODS

This case-control study included 1,556 participants (1,115 cases; 441 controls) from Delhi-NCR. Maternal residential addresses were geocoded to estimate periconceptional exposure (at conception, one month pre- and post-conception) to major air pollutants [PM2.5, PM10, NO2, CO, SO2, O3, PM2.5+ PM10, and Air Quality Index (AQI)]. Associations were analysed using multinomial regression.

RESULTS

Sixteen Bonferroni-corrected Adjusted odds ratio (AOR) were observed in the study. Preconception exposure to poor AQI [AOR = 2.54 (1.60-4.04)] and PM10 [AOR = 2.82 (1.69-4.71)] increased the odds of simple CHD. At conception, poor AQI was associated with all CHDs [AOR = 2.48 (1.60-3.84)], acyanotic [AOR = 2.68 (1.70-4.24)], and simple CHDs [AOR = 2.71 (1.67-4.39)]. Post-conception exposure showed the strongest associations: poor AQI-All CHD [AOR = 2.74 (1.78-4.22)], acyanotic [AOR = 2.89 (1.84-4.56)], simple CHD [AOR = 2.85 (1.76-4.61)]; PM10-All CHD [AOR = 3.36 (2.05-5.52)], acyanotic [AOR = 3.50 (2.09-5.84)], simple CHD [AOR = 3.95 (2.31-6.76)], and moderate CHD [AOR = 3.64 (1.91-6.91)]. VSD was consistently associated with PM10 preconception [AOR = 3.13 (1.80-5.47)], poor AQI at conception [AOR = 3.18 (1.82-5.53)], and both poor AQI [AOR = 4.01 (2.28-7.08)] and PM10 [AOR = 4.35 (2.41-7.83)] post-conception.

CONCLUSIONS

To our knowledge, this first Indian study demonstrates that periconceptional exposures to poor AQI and PM10 is significantly associated with increased odds of CHD, with the post-conception period emerging as the most critical window. These findings highlight the urgent need for larger nationwide cohorts and targeted exposure-reduction strategies in early pregnancy.