Female participants were screened for pregnancy with urine pregnancy testing. Participants completed the baseline survey, which included questions about demographics, including ethnicity (classified categorically as white, African-American, Hispanic, Asian, and Other), and smoking behaviors, including the frequency and quantity of cigarette smoking and the types of cigarettes smoked. They were asked when they first tried smoking, when they first smoked a whole cigarette, and when they began smoking regularly. Participants completed the modified Fagerström Tolerance Questionnaire (mFTQ)(29) scale to measure nicotine dependence.
