Dual use of cigarettes and electronic nicotine delivery systems during pregnancy and the risk of small for gestational age neonates.

PURPOSE The purpose of this study was to estimate the effect of cigarette smoking and electronic nicotine delivery systems (ENDS) use during pregnancy on small for gestational age (SGA). METHODS We used data from the 2016-2017 Arkansas Pregnancy Risk Assessment Monitoring System, estimated the risk ratio (RR) for SGA for maternal prenatal cigarette smoking-only use, cigarette smoking, and ENDS use (i.e., dual use), with no prenatal tobacco use as referent, accounting for the complex survey design. We also explored these effects for women who stopped smoking cigarettes during pregnancy among cigarette smokers and dual users. RESULTS Estimated adjusted RR for SGA for cigarette-only users was 1.7 (95% confidence interval [CI]: 1.1, 2.7), and 1.8 (95% CI: 1.0, 3.4) for dual users. These RR estimates increased after correcting for tobacco use misclassification. Women who were dual users (cigarette smokers and ENDS users) and continued using ENDS but stopped smoking cigarettes had an increased risk for SGA compared with nontobacco users, 3.2 (95% CI: 1.5, 6.6). CONCLUSIONS Our results in a population representative sample are consistent with the hypothesis that exposure to both maternal cigarette smoking and ENDS use increased the risk of SGA. Dual users still had an elevated risk of SGA after smoking cessation.