[영문]Background.Pregnant smokers represent a major public health challenge. The objective of this study was to determine trends in smoking during pregnancy in Tennessee, a state with one of the highest smoking burdens in the nation, and to confirm characteristics of high-risk groups to target for smoking prevention.Methods.Population-based cohort study of pregnant women in Tennessee who delivered live births from 1990?2001. Trends in smoking were determined by maternal age, race and insurance status using vital records and Medicaid data. Characteristics of women who smoked during pregnancy were described for 2001.Results.Among 900,986 pregnant women in the cohort, there were statewide decreases in smoking rates during pregnancy; however, smoking among pregnant women younger than 25 years in Medicaid increased from 1996 to 2001: among whites from 31% to 34%, and among blacks from 6% to 9% (P values for trend shifts qqqlt; 0.0001). Characteristics of pregnant women who smoked during pregnancy included white race, Medicaid enrollment, nonurban residence, and less than a high school education.Conclusions.Smoking rates increased significantly among pregnant women qqqlt; 25 years enrolled in Medicaid between 1996 and 2001. Tennessee needs smoking cessation and prevention efforts that target young, low-income women with less than a high school education.