Association between gestational exposure and risk of orofacial clefts: a systematic review and meta-analysis

BACKGROUND: The occurrence of orofacial Clefts (OFCs) is a congenital disease caused by many factors. According to recent studies, air pollution has a strong correlation with the occurrence of OFCs. However, there are still some controversies about the current research results, and there is no relevant research to review the latest results in recent years. OBJECTIVE: In this paper, the authors conducted a systematic review and meta-analysis to explore the correlation between ambient air pollution and the occurrence of neonatal OFCs deformity. METHODS: We searched Pubmed, Web of science, and Embase databases from the establishment of the database to May 2023. We included observational studies on the relationship between prenatal exposure to fine particulate matter 2.5 (PM2.5), fine particulate matter 10 (PM10), sulfur dioxide (SO2), nitrogen dioxide (NO2), ozone (O3), carbon monoxide (CO) and the risk of cleft lip (CL), cleft palate (CP), cleft lip with or without palate (CL/P). the Newcastle-Ottawa quality assessment scale (NOS) was used to evaluate the quality of the literature. Funnel plot and Egger’s regression were used to verify the publication bias. Random effect model or fixed effect model was used to estimate the combined relative risk (RR) and 95% confidence interval (95%CI). RESULTS: A total of eleven studies were included in this study, including four cohort studies and seven case-control studies, including 22,453 cases of OFCs. Ten studies had low risk of bias and only one study had high risk of bias. Three studies reported that PM(2.5) was positively correlated with CL and CP, with a combined RR and 95%CI of 1.287(1.174,1.411) and 1.267 (1.105,1.454). Two studies reported a positive correlation between O(3) and CL, with a combined RR and 95%CI of 1.132(1.047,1.225). Two studies reported a positive correlation between PM(10) and CL, with a combined RR and 95%CI of 1.108 (1.017,1.206). No association was found between SO(2), CO, NO(2) exposure during pregnancy and the risk of OFCs. CONCLUSION: The results of this study showed that there was a significant statistical correlation between exposure to PM(10), PM(2.5), O(3) and the risk of OFCs in the second month of pregnancy. Exposure assessment, research methods and mechanisms need to be further explored. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12884-023-06104-4.