Maternal ambient air pollution exposure preconception and during early gestation and offspring congenital orofacial defects

Background: Maternal air pollution exposure has been related to orofacial clefts but the literature is equivocal. Potential chronic preconception effects have not been studied. Objectives: Criteria air pollutant exposure during three months preconception and gestational weeks 3-8 was studied in relation to orofacial defects. Methods: Among 188,102 live births and fetal deaths from the Consortium on Safe Labor (2002-2008), 63 had isolated cleft palate (CP) and 159 had isolated cleft lip with or without cleft palate (CL ±CP). Exposures were estimated using a modified Community Multiscale Air Quality model. Logistic regression with generalized estimating equations adjusted for site/region and maternal demographic, lifestyle and clinical factors calculated the odds ratio (OR) and 95% CI per interquartile increase in each pollutant. Results: Preconception, carbon monoxide (CO; OR=2.24; CI: 1.21, 4.16) and particulate matter (PM) ≤10μm (OR=1.72; CI: 1.12, 2.66) were significantly associated with CP, while sulfur dioxide (SO₂) was associated with CL ±CP (OR=1.93; CI: 1.16, 3.21). During gestational weeks 3-8, CO remained a significant risk for CP (OR=2.74; CI: 1.62, 4.62) and nitrogen oxides (NO_x; OR=3.64; CI: 1.73, 7.66) and PM ≤2.5μm (PM_2.5; OR=1.74; CI: 1.15, 2.64) were also related to the risk. Analyses by individual week revealed that positive associations of NO_x and PM_2.5 with CP were most prominent from weeks 3-6 and 3-5, respectively. Conclusions: Exposure to several criteria air pollutants preconception and during early gestation was associated with elevated odds for CP, while CL ±CP was only associated with preconception SO₂ exposure.