PROJECT ABSTRACT Electronic cigarettes (e-cigarettes), since their first introduction in the world market in 2004, have been advertised as a healthier alternative and a smoking cessation aid to existing tobacco products. has youth E-cigarette use been increased dramatically in the recent years, becoming the most commonly used smoking product in and young adults since 2014. Itis particularly appealing to pregnant women smokers who are motivated to change their smoking habits and to improve their and their fetus' health. However, the potential adverse effects of e-cigarettes as shown in the recent outbreak, whether it poses an increased risk to women and their developing fetus, is unknown. The overarching objectives of the study are 1) to determine the longitudinal pattern of women's smoking from preconception to perinatal period and over time, 2) to determine the association between pregnancy e-cigarette use and pregnancy, perinatal, and infant related adverse outcomes, and 3) to determine the association between pregnancy e-cigarette use and metabolic profile measured at birth. We propose to conduct a surveillance study of women who gave live births between 2016- 2018 and participated in the Centers for Disease Control and Prevention (CDC) initiated Pregnancy Risk Assessment Monitoring System (PRAMS) survey. Detailed smoking information, including conventional cigarette and e-cigarette use during preconception, 3rd trimester of pregnancy, and post-delivery have been collected. We will further link PRAMS study of women from Tennessee and Iowa to newborn metabolic screening (NBS) program data to identify and validate metabolic profile measured at birth that are associated with secondhand in utero e-cigarette and conventional cigarette exposure. Our proposed study will address important questions and will be of significant public health importance. It will provide much needed information about pregnancy e-cigarette use. Results will certainly inform policy and drive public health initiative, providing evidence for targeted maternal-fetal interventions in smoking cessation and in mitigating adverse effects of smoking on outcomes. It may further provide insight in addressing recent outbreak of e-cigarette, or vaping, product use associated lung injury (EVALI).