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Passive smoking in the etiology of non-syndromic orofacial clefts: A systematic review and meta-analysis

Sabbagh, Heba J., Hassan, Mona Hassan Ahmed, Innes, Nicola P.T. ORCID:, Elkodary, Heba M., Little, Julian and Mossey, Peter A. 2015. Passive smoking in the etiology of non-syndromic orofacial clefts: A systematic review and meta-analysis. PLoS ONE 10 (3) , e0116963. 10.1371/journal.pone.0116963

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Background Studies have found a consistent positive association between maternal smoking and non-syndromic orofacial clefts (NSOFC). However, no comprehensive assessment of the association between NSOFC and passive smoking has been undertaken. This systematic review and meta-analysis explores the relationship between maternal passive smoking and NSOFC, and compares the associations between passive and active smoking. Methods and Findings Search strategy, inclusion / exclusion criteria, and data extraction from studies reporting maternal passive smoking and NSOFC was implemented without language restrictions. Risks of bias in the identified studies were assessed and this information was used in sensitivity analyses to explain heterogeneity. Meta-analysis and meta-regression of the extracted data were performed. Egger's test was used to test for small study effects. Fourteen eligible articles were identified. Maternal passive smoking exposure was associated with a twofold increase in risk of NSOFC (odds ratio: 2.11, 95% confidence interval: 1.54–2.89); this was apparent for both cleft lip with and without palate (OR: 2.05, 95% CI: 1.27–3.3) and cleft palate (OR: 2.11, 95% CI: 1.23–3.62). There was substantial heterogeneity between studies. In the studies that provided data enabling crude and adjusted odd ratios to be compared, adjustment for potential confounders attenuated the magnitude of association to about a 1.5-fold increase in risk. Conclusion Overall, maternal passive smoking exposure results in a 1.5 fold increase in risk of NSOFC, similar to the magnitude of risk reported for active smoking, but there is marked heterogeneity between studies. This heterogeneity is not explained by differences in the distribution of cleft types, adjustment for covariates, broad geographic region, or study bias/quality. This thorough meta-analysis provides further evidence to minimize exposure to environmental tobacco smoke in policy making fora and in health promotion initiatives.

Item Type: Article
Date Type: Published Online
Status: Published
Schools: Dentistry
Additional Information: This is an open access article distributed under the terms of the Creative Commons Attribution License.
Publisher: Public Library of Science
ISSN: 1932-6203
Date of First Compliant Deposit: 2 September 2020
Date of Acceptance: 16 December 2014
Last Modified: 05 May 2023 21:22

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