Maternal exposure to fine particulate matter and congenital heart defects during preconception and pregnancy period: A cohort-based case-control study in the Taiwan maternal and child health database.

Background: Few studies have explored the association between maternal exposure to particulate matter with an aerodynamic diameter of ≤2.5 μm (PM _2.5 ) and congenital heart defects occurring before and during pregnancy. We aimed to investigate the association and the critical time windows between the maternal exposure to PM _2.5 and congenital heart defects.
Method: We conducted a cohort-based case-control study of 507,960 participants obtained from the Taiwan Maternal and Child Health Database between 2004 and 2015. We applied satellite-based spatiotemporal models with 1-km resolution to calculate the average PM _2.5 concentration during preconception and the specific periods of pregnancy. We also performed conditional logistic regression with distributed lag non-linear models (DLNMs) to assess the effects of weekly average PM _2.5 on both congenital heart defects and their isolated subtypes, as well as the concentration-response relationships.
Results: In DLNMs, exposure to PM _2.5 (per 10 μg/m3) during weeks 7-12 before conception and weeks 3-9 after conception was associated with congenital heart defects. The strongest association at 12 weeks before conception (odds ratio [OR] = 1.026, 95% confidence intervals [CI]: 1.012-1.040) and 7 weeks after conception (OR = 1.024, 95% CI: 1.012-1.036) for every 10 μg/m ³ increase in PM _2.5 concentration. In modification analysis, strongest associations were observed for low SES.
Conclusions: Our study revealed that exposure to ambient PM _2.5 raises the risk of congenital heart defects, particularly among individuals with lower socioeconomic status. Moreover, our findings suggest that preconception exposure to PM _2.5 may be a crucial period for the development of congenital heart defects.
Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
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