Prevalence and patterns of cigarette smoking before and during early and late pregnancy according to maternal characteristics: the first national data based on the 2003 birth certificate revision, United States, 2016.

Despite the high prevalence of high intensity smoking before and during pregnancy, future intervention strategies need to focus on the proportion of low intensity quitters and reducers, who are ready to stop smoking. Continual monitoring of trends in smoking intensity patterns is necessary, including neonatal outcomes over time.