. 2018 Sep 25;15(10):2096. doi: 10.3390/ijerph15102096

Table 2.

External air pollution and congenital heart disease: Main findings from the literature.

Author Ref.	Article Type	All CHD or Any CHD Subtypes	Study Limitations
Vrijheid et al. [30]	Meta-analysis	NO₂: COA: OR 1.17 (25% CI 1.00–1.36); TOF: OR 1.2 (25% CI 1.02, 1.42) SO₂: COA: OR 1.07 (25% CI 1.01, 1.13); TOF: OR 1.03 (25% CI 1.01, 1.05) PM₁₀: ASD: OR 1.14 (95% CI 1.01, 1.28)	Studies were few, high heterogeneity, different methods and extent of exposure measurement, different classifications of CHD and diagnostics, assumes a linear dose response relationship, generally do not consider effect of genetics, all confounding factors or pregnancy ending in death.
Chen et al. [1]	Meta-analysis	NO₂: COA: OR 1.20 (25% CI 1.02, 1.41). Other CHDs and pollutants not significant.	As per Vrijheid et al. Did not meta-analyse where only a few studies.
Ren et al. [32]	Population based study	All CHDs: PM₁₀ exposure of ≥92 μg m⁻³ OR 1.16 (95% CI: 1.06, 1.28)	Machine learning study, but insufficient studies of this nature to determine its usefulness.
Liu et al. [33]	Hospital-based case control study	PM₁₀ exposure associated with: All CHDs: OR 1.28 (95% CI: 1.03, 1.61) ASDs: ORs 1.29 to 2.17 (95% CI: 1.17, 2.23) VSDs: OR 1:19 (95% CI:1.00, 1.43) PDA: ORs 1.54 to 1.63 (95% CI: 1.06, 3.24) TOF: OR 1:44 (95% CI: 1.01, 2.19)	Uncertainty over exposure monitoring. Pregnancy duration <20 weeks was ignored, leading to bias as a CHD may have been the reason. Early pregnancy residential location was used, which is more representative but makes comparison with other studies using birth location more difficult. Few potentially confounding factors assessed.

Abbreviations: COA: Coarctation of the aorta; TOF: Tetralogy of Fallot; ASD: Atrial septal defect; VSD: Ventricular septal defect; PDA: Patent ductus arteriosus.