INTRODUCTION: While a relationship between maternal tobacco exposure and development of orofacial clefts in the child has been established for some time, the actual degree of risk conferred is not well quantified.1–3 A better understanding of this risk would benefit prenatal specialists in the counseling of prospective parents.4 The purpose of this study was to quantify the risk for cleft lip and/or cleft palate (CLP) associated with maternal tobacco exposure.
METHODS: A case-control study was conducted at the Cleft Hospital and the Bashir Hospital in Gujrat, Pakistan from December 2015 to December 2016. All new cases of CLP at the Cleft Hospital were included in the study. Infants and children of three years of age or less at the Bashir Hospital were concurrently chosen to serve as control cases if they had no congenital malformations, were born or living in the same area as the patients in the study with CLP, and were of comparable socioeconomic standing to those patients. Bivariate analyses were performed to identify risk factors associated with CLP. These variables were then included alongside maternal tobacco exposure (whether one or both parents smoke) in a multiple logistic regression to calculate the adjusted odds ratio of developing CLP associated with tobacco exposure.
RESULTS: A total of 329 patients with CLP and 131 controls were included in the study. Upon bivariate analysis, the following factors were associated with CLP: maternal tobacco exposure (p<0.001), complications during pregnancy (p<0.001), maternal hypertension (p=0.01), mother not on any medications (p<0.001), mother not receiving vaccinations (p<0.001), and lower socioeconomic status (p<0.001). After adjustment for these variables, having a smoking parent was associated with a 2.09 times increased odds of the child developing CLP (95% CI 1.22–3.58). Complications during pregnancy (OR=2.38, 95% CI 1.45–3.90), mother receiving vaccinations (OR = 0.32, 95% CI 0.16–0.64), and higher socioeconomic status (OR = 0.15, 95% CI 0.04–0.63) were also associated with CLP.
CONCLUSION: While previous studies have consistently shown maternal tobacco exposure to be associated with development of orofacial clefts in the child, this study identifies and accounts for possible confounding variables in a case-control design, thereby providing a quantified estimate of the risk conferred by maternal tobacco exposure. This finding will be of value to providers in the context of perinatal counseling.
1. Wyszynski DF, Duffy DL, Beaty TH. Maternal Cigarette Smoking and Oral Clefts: A Meta-analysis. Cleft Palate-Craniofacial J. 1997;34(3):206–210. doi:10.1597/1545–1569(1997)034<0206:MCSAOC>2.3.CO;2.
2. Little J, Cardy A, Munger RG. Tobacco smoking and oral clefts: a meta-analysis. Bull World Health Organ. 2004;82(3):213–218.
3. Xuan Z, Zhongpeng Y, Yanjun G, et al. Maternal active smoking and risk of oral clefts: a meta-analysis. Oral Surg Oral Med Oral Pathol Oral Radiol. 2016;122(6):680–690. doi:10.1016/j.oooo.2016.08.007.
4. Elahi MM, Jackson IT, Elahi O, et al. Epidemiology of cleft lip and cleft palate in Pakistan. Plast Reconstr Surg. 2004;113(6):1548–1555. doi:10.1097/01.PRS.0000117184.77459.2B.