Smoking and pregnancy: A comparison of Mexican-American and non-hispanic white women

Objective: To describe ethnic differences in tobacco use during pregnancy in a clinical population of Mexican-American and non-Hispanic white women. Methods: Subjects were randomly selected from all patients attending a university-based obstetrics clinic in Tucson, Arizona. Of 555 subjects selected, 367 were interviewed and had their urinary cotinine levels measured. The 37 subjects who refused an interview and the 136 who were selected but not interviewed did not differ from other subjects regarding ethnicity, education, obstetric history, or smoking status. The interviewer gathered standard demographic and obstetric information as well as data on smoking behavior. Subjects were interviewed in Spanish or English by a bilingual interviewer using a standardized questionnaire. Statistical techniques included χ² test, t test, and logistic regression. Results: The odds for Mexican-American women to have been smokers were 3.39 times lower than for non-Hispanic white women. The odds of quitting during pregnancy were 4.71 times higher for Mexican-Americans (95% confidence interval 1.66-13.38). Urinary cotinine values verified the latter rates. Mexican-American smokers reported smoking significantly fewer cigarettes than non-Hispanic white women (t = 2.34, P <.05). Conclusions: In comparing Mexican-American and non-Hispanic white women, we found marked differences in smoking behavior during pregnancy. Mexican-Americans were nearly three times more likely to quit than non-Hispanic whites, and those who continued to smoke showed greater reductions in cigarettes per day. These results show behavioral changes in Mexican-Americans during pregnancy that meaningfully alter the risk profile for the fetus. Understanding the basis for this behavioral change may facilitate the development of preventive measures for other ethnic groups. (Obstet Gynecol 1994;84:1033-7).