Maternal exposure to ambient particulate matter 10 μm or less in diameter before and after pregnancy, and anencephaly risk: A population-based case-control study in China.

Background: There is no epidemiological evidence on the effects of maternal exposure to ambient particulate matter 10 μm or less in diameter (PM) and anencephaly risk in offspring.

Methods: We conducted a population-based case-control study in Liaoning Province, China. The case group consisted of 663 cases with anencephaly and the control group consisted of 7950 healthy infants from the Maternal and Child Health Certificate Registry of Liaoning Province that were born between 2010 and 2015. Daily PM concentrations were obtained from 77 monitoring stations located within the study area. A multivariable logistic regression model was established to calculate the adjusted odds ratios (ORs) and 95% confidence intervals (CIs).

Results: Maternal PM exposure was significantly associated with an increased risk of anencephaly at three months before conception (highest versus lowest tertile: OR = 1.74, 95% CI: 1.29-2.34; per 10 μg/m increment: OR = 1.13, 95% CI: 1.06-1.20) and three months after conception (highest versus lowest tertile: OR = 1.93, 95% CI: 1.44-2.60; per 10 μg/m increment: OR = 1.01, 95% CI: 0.95-1.08). The evaluation of shorter exposure windows revealed similar associations for PM exposure from the third month before pregnancy to the third month after pregnancy.

Conclusions: Maternal PM exposure is positively associated with anencephaly risk during the critical period of neural system development.