Use of US birth certificate data to estimate the risk of maternal cigarette smoking for oral clefting.
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.
Wyszynski
Diego F
DF
Department of Medicine, Boston University School of Medicine, Boston, Massachusetts 02118, USA. dfw@bu.edu.
Wu
Tianxia
T
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