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

<bold>Objective: </bold>To examine the prevalence and the changing pattern of e-cigarette use from preconception to pregnancy.<bold>Methods: </bold>This is a cross-sectional study using data from the multi-site Pregnancy Risk Assessment Monitoring System in the United States, 2016-2017. All participating mothers with information on e-cigarette use before and during pregnancy were included. Self-reported information about e-cigarette use were assessed using questionnaires. Weighted prevalences of e-cigarette use before and during pregnancy were calculated. Multivariable logistic regressions were used to examine the association between various demographic characteristics and e-cigarette use before or during pregnancy.<bold>Results: </bold>This study included 69,508 pregnant women from 38 states in the United States. The weighted prevalence of e-cigarette use before pregnancy and during the last 3 months of pregnancy was 3.6% (95% CI 3.4%-3.9%) and 1.1% (0.9%-1.2%), respectively. The prevalence varied across states, ranging from 1.3% to 8.3% for e-cigarette use before pregnancy and from 0.1% to 3.4% for e-cigarette use during the last 3 months of pregnancy. Among women who used e-cigarettes before pregnancy, 24.4% (21.7%-27.1%) continued to use e-cigarettes during pregnancy. Among women who used e-cigarettes during pregnancy, 62.3% (56.5%-68.0%) were dual users. In multivariable analyses, cigarette smoking was most strongly associated with e-cigarette use. The adjusted odds ratio comparing smokers with non-smokers before pregnancy was 11.0 (95% CI 9.3-13.1) for e-cigarette use before pregnancy and 6.7 (95% CI 4.4-10.3) for e-cigarette use during pregnancy.<bold>Conclusions: </bold>Using data from 38 states in the USA, we showed geographical variations in the prevalence of e-cigarette use before and during pregnancy. Among women who used e-cigarettes before pregnancy, a quarter of them continued to use e-cigarettes during pregnancy. Conventional cigarette use is a strong risk factor for e-cigarette use before and during pregnancy. The prevalence of e-cigarette use needs to be monitored continuously.<bold>Implications: </bold>This study provides important information to understand the status and changing patterns of e-cigarette use in pregnant women in the USA. 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. [ABSTRACT FROM AUTHOR]