Association Between Maternal Exposure to Indoor Air Pollution and Offspring Congenital Heart Disease: A Multi-Hospital Case-Control Study in East China

Background: Previous research has suggested an association between maternal exposure to ambient air pollutants and the risk of congenital heart defects (CHDs). However, the effect of individual prenatal exposure to indoor air pollutants on CHD occurrence has not been reported. Methods We carried out a hospital-based case-control study to investigate the association between personal air pollution exposure during pregnancy and the risk of CHDs in offspring. A total of 34 cases and 72 controls were included in this study from two hospitals in East China. We investigated maternal and residential environmental characteristics using a questionnaire and obtained personal indoor air samples to assess particulate matter (PM) and volatile organic compounds (VOCs) from 22–30 gestational weeks; formaldehyde, benzene, toluene, xylene, total VOCs (TVOCs), PM 10 , and PM 2.5 were assessed. Logistic regression was performed to assess associations and interactions among individual indoor air pollutants and CHDs after adjusting for confounders. The potential residential environmental factors affecting the risks of indoor air pollutants on CHDs were also assessed. Results Median TVOC (0.430 vs. 0.005 mg/m 3 , P < 0.001), PM 2.5 (12.00 vs. 8.00 µg/m 3 , P = 0.037) and PM 10 (13.50 vs. 8.00 µg/m 3 , P = 0.028) exposure levels in cases were significantly higher than those in controls. In a regression model adjusted for confounders, exposure to high levels of indoor TVOCs, PM 2.5 and PM 10 during pregnancy was associated with risks for CHDs and the occurrence of some major CHD subtypes in offspring. These risk effects were enhanced among pregnant woman living in a newly renovated house or near heavy-traffic roads but were mitigated by household usage of smoke ventilators when cooking. We observed a positive interaction of maternal exposure to TVOCs and PM 2.5 in regard to the risk for CHDs. Conclusions Maternal exposure to indoor VOCs and PMs may increase the risk of giving birth to foetuses with CHDs.