Prevalence and Distribution of Electronic Cigarette Use Before and During Pregnancy Among Women in 38 States of the United States.

This study provides important information to understand the status and changing patterns of e-cigarette use in pregnant women in the United States. Among pregnant women in 38 states in the United States, 3.6% of them used e-cigarettes during the 3 months before pregnancy and 1.1% used them during the last 3 months of pregnancy. The prevalence varied across states. A quarter of women who used e-cigarettes before pregnancy continued to use e-cigarettes during pregnancy. Cigarette smoking is the strongest predictor of e-cigarette use. Future research about health effects of e-cigarette use during pregnancy is in urgent need.