Maternal characteristics. An extended prenatal questionnaire is used at recruitment and at the 6-month follow-up. Based on the prior literature on the predictors of postpartum relapse, the questionnaire includes demographics (such as age, education, and ethnicity), health history (prior pregnancies history, contraception use and feelings about the pregnancy), mental health (depressive symptoms, stress, anxiety), nicotine dependence before quitting, an extensive section on smoking knowledge and attitudes, other substance use, breast feeding, and having a life partner who smokes (as reported by the new mother).