Background Current literature describes limited and controversial evidence on the associations between maternal preconception and first trimester exposure to particulate matter with a diameter ≤10 µm (PM10) and the risk of oral cleft (OC).
Methods We conducted a case–control study involving 3086 OC cases and 7950 controls, registered in the Maternal and Child Health Certificate Registry in Liaoning Province between 2010 and 2015. PM10 concentrations were obtained from the Environment Protection Bureau. The exposure windows included the 3 months before pregnancy, the first trimester and the individual months. Unconditional logistic regression model was performed to estimate the OR and 95% CI for the association between PM10 exposure and the risk of OC, cleft lip only (CLO), cleft palate only (CPO), and cleft lip and palate (CLP).
Results Maternal PM10 exposure was positively associated with an increased risk for OC during the 3 months preconception (per 10 µg/m3 increment: OR=1.04, 95% CI 1.01 to 1.07; highest vs lowest quartile: OR=1.23, 95% CI 1.04 to 1.45) and the first trimester (per 10 µg/m3 increment: OR=1.05, 95% CI 1.02 to 1.08; highest vs lowest quartile: OR=1.37, 95% CI 1.15 to 1.64). Analyses based on individual months presented similar positive associations, particularly in the second month of pregnancy (OR=1.77, 95% CI 1.51 to 2.09) for highest versus lowest quartile. In the subtype analysis, stronger associations were observed for CLO, whereas there was negligible evidence for CPO and CLP. Sensitivity analyses using propensity score matching generated similar findings.
Conclusions Our study provides evidence that PM10 exposure during the 3 months preconception and the first trimester increases the risk of OC.
- air pollution
- congenital anomalies
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F-HL and H-XD contributed equally.
Contributors F-HL: writing, original draft preparation. H-XD: writing, original draft preparation. T-TG: writing, reviewing and editing. J-YZ: writing, reviewing and editing. JL: data curation. Z-JC: visualisation. L-LL: software. Y-LC: investigation. SL: visualisation. C-ZJ: software. Y-HH: conceptualisation, methodology. Y-HZ: validation. Q-JW: supervision.
Funding This work was supported by the National Key R&D Program of China (No. 2017YFC0907401 to Y-HZ), the Liaoning Providence science and technology project (2015225025 to Y-HH), the Shenyang science and technology project (F15-139-9-09 to Y-HH), the LiaoNing Revitalization Talents Program (no. XLYC1907102 to Q-JW and No. XLYC1802095 to Y-HZ), and 345 Talent Project (to Q-JW).
Competing interests No competing interests.
Patient consent for publication Not required.
Provenance and peer review Not commissioned; externally peer reviewed.
Data availability statement Data are available upon reasonable request.
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