Cleft Lip Risks Associated with Cigarettes

What impact does smoking have on women having children with certain craniofacial deformities such as cleft lip or cleft palate?  One interesting study that addresses this issue is called, "Maternal Cigarette Smoking during Pregnancy and the Risk of Having a Child with Cleft Lip/Palate" by Chung, Kevin C. M.D., M.S.; Kowalski, Christine P. M.P.H.; Kim, Hyungjin Myra Sc.D.; Buchman, Steven R. M.D. - Plastic & Reconstructive Surgery: February 2000 - Volume 105 - Issue 2 - pp 485-491.  Here is an excerpt: "Abstract - Maternal cigarette smoking during pregnancy as a risk factor for having a child with cleft lip/palate has been suggested by several epidemiologic studies. However, most of these studies contained small sample sizes, and a clear association between these two factors could not be established. The U.S. Natality database from 1996 and a case-control study design were used to investigate the association between maternal smoking during pregnancy and having a child with cleft lip/palate.  The records of 3,891,494 live births from the 1996 U.S. Natality database were extracted to obtain cleft lip/palate cases and random controls. The National Center for Health Statistics collects maternal and newborn demographic and medical data from the birth certificates of all 50 states. New York (excluding New York City), California, Indiana, and South Dakota did not collect smoking data, and the data from these states were excluded from the analysis. A total of 2207 live births with cleft lip/palate cases were identified, and 4414 controls (1:2 ratio) were randomly selected (using the SAS program) from live births with no congenital defects. Odds ratios and 95 percent confidence intervals were determined from logistic regression models, adjusting for confounding variables, including maternal demographic and medical risk factors."

Another interesting study is called, "Brief Communication Nature Genetics 29, 141–142 (1 October 2001).  Mutation of PVRL1 is associated with sporadic, non-syndromic cleft lip/palate in northern Venezuela Mehmet A.  , Koji Suzuki , Marie M. Tolarova , Tania Bustos , Iglesias & Richard A. Spritz Here is an excerpt: Abstract - Non-syndromic cleft lip with or without cleft palate (CL/P, MIM 119530) is among the most common of major birth defects. Homozygosity for a nonsense mutation of PVRL1, W185X, results in an autosomal recessive CL/P syndrome on Margarita Island."

Another interesting study is called, "Does Maternal Cigarette Smoking During Pregnancy Cause Cleft Lip and Palate in Offspring?" by Muin J. Khoury, MD, PhD; Marco Gomez-Farias, MD, MPH; Joseph Mulinare, MD, MSPH - Am J Dis Child. 1989;143(3):333-337. Vol. 143 No. 3, March 1989.  Here is an excerpt: "Abstract - To investigate the relationship between maternal cigarette smoking and the risk of oral clefts in offspring, we examined data from the Atlanta Birth Defects Case-Control Study, which included 238 cases of cleft lip with or without cleft palate and 107 cases of cleft palate ascertained by the Metropolitan Atlanta Congenital Defects Program from 1968 through 1980. In all, 2809 infants who served as controls were frequency matched to cases by race, period of birth, and hospital of birth. Maternal periconceptional exposures to smoking were investigated through use of a structured questionnaire. Smoking exposure was defined as reported maternal smoking during the periconceptional period (from 3 months before conception to 3 months after pregnancy began). Offspring of smoking mothers were 1.6 and 2.0 times more likely than offspring of nonsmoking mothers to have isolated cleft lip with or without cleft palate and cleft palate, respectively. On the other hand, offspring of smoking mothers were not at increased risk of having cleft palate or cleft lip with or without cleft palate that are associated with other defects. Adjustment for potential confounding variables did not alter these results. A relatively modest effect of smoking may be explained by the presence of underlying etiologic heterogenity in oral clefts and differential susceptibility to smoking. Because of the inconsistencies in the literature on the relationship between smoking and oral clefts, these results suggest the need to refine oral clefts into more homogeneous subgroups in epidemiologic studies of these defects."

We all owe a debt of gratitude to these researchers for their fine work and dedication.  For more information, please read the studies in their entirety.