title: Use of US birth certificate data to estimate the risk of maternal cigarette smoking for oral clefting.
abstract: OBJECTIVE
  The purpose of this study was to evaluate the relationship between maternal cigarette smoking and the risk of having an offspring with an oral cleft.
  
  
  METHODS
  This was a large population-based, matched case-control study derived from the United States Natality database for 1997.
  
  
  METHODS
  The sample consisted of 2029 cases with non-syndromic oral clefts and 4050 non-malformed controls. Controls were matched to cases on mother's and father's race and child's sex, county of birth, and month of birth. This sample was selected from a total of 3,093,821 births in the United States, which represents 80% of all births in this country during 1997.
  
  
  RESULTS
  The association between maternal cigarette smoking and oral clefts in the offspring was close to the null (odds ratio 1.16; 95% confidence interval (CI) 1.01 to 1.33; one-sided Fisher exact test p =.0207). The comparison and pooling of results to those of a similar study that used the U.S. Natality database for 1996 resulted in a common Mantel-Haenszel odds ratio of 1.33 (95% CI 1.21 to 1.46). The dose-response analysis was slightly significant for all levels of maternal smoking.
  
  
  CONCLUSIONS
  This large study confirms that smoking during pregnancy is only a minor risk factor for oral clefting in the offspring.
authors.affiliation: Department of Medicine, Boston University School of Medicine, Boston, Massachusetts 02118, USA. dfw@bu.edu.
authors.forename: Diego F
authors.initials: DF
authors.lastname: Wyszynski
authors.forename: Tianxia
authors.initials: T
authors.lastname: Wu
mesh_terms: D000328:Adult; D000367:Age Factors; D000428:Alcohol Drinking / Q000453:epidemiology; D001719:Birth Certificates; D016022:Case-Control Studies; D016009:Chi-Square Distribution; D002971:Cleft Lip / Q000453:epidemiology*; D002972:Cleft Palate / Q000453:epidemiology*; D016001:Confidence Intervals; D019992:Databases as Topic; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D008423:Maternal Age; D016017:Odds Ratio; D011159:Population Surveillance; D011247:Pregnancy; D011248:Pregnancy Complications / Q000453:epidemiology*; D011297:Prenatal Exposure Delayed Effects; D044469:Racial Groups; D012307:Risk Factors; D012737:Sex Factors; D012907:Smoking / Q000453:epidemiology*; D013223:Statistics as Topic; D014481:United States / Q000453:epidemiology