Background: Cigarette smoking during pregnancy is associated with increased infant mortality, low birth weight, and other poor outcomes. Pregnant patients who try to quit smoking are increasingly turning to electronic cigarettes (e-cigarettes), as they believe it is safer for the fetus. However, little is known about the relative safety of e-cigarettes as compared to cigarettes during pregnancy. We evaluated whether e-cigarette use during pregnancy was associated with fewer infant health complications, lower toxicant biomarker levels, and better birth outcomes compared to cigarette smoking. We examined toxicant levels at delivery, birth outcomes, and health at 3-months postpartum of infants born to women who exclusively used e-cigarettes, only cigarettes, and those who used both during pregnancy. Our objective is to understand the role of e-cigarettes in reducing infant health complications, improve physician counseling regarding e-cigarette safety, and evaluate e-cigarettes as a harm-reduction tool for pregnant patients who smoke.

Methods: This prospective cohort study followed n=179 (n=100 exclusive cigarette, n=40 dual use, and n=39 exclusive e-cigarette) pregnant women. At birth, neonatal urine and cord blood were analyzed for the tobacco metabolite NNAL; volatile organic compounds benzene, acrylamide, acrolein, acrylonitrile; and nicotine metabolite (cotinine) levels. Birth outcomes, such as APGAR score, gestational age, and weight were collected from medical charts. 3-month postpartum surveys assessed infant health complications, such as infection, hospitalizations, and respiratory problems. Kruskal Wallis and Chi-square tests were conducted using SPSS statistical software.

Results: Infants of women who exclusively smoked cigarettes had the highest mean NNAL level at birth (30.32, SD=43.39), followed by those who dual used (17.24, SD=15.90), and those who used e-cigarettes (2, SD= .77, p=0.004). Similarly, infants of women who exclusively smoked cigarettes and who dual used had the highest mean acrylonitrile values (22.74, SD= 34.32, and 23.06, SD=22.97, respectively), while those born to exclusive e-cigarette users had the lowest (18.16, SD=56.91, p=0.008). No differences were observed in cotinine levels, birth outcomes, or 3-month postpartum health complications across the groups.

Conclusion: Exclusive maternal e-cigarette use during pregnancy correlates with lower infant NNAL and acrylonitrile levels at birth. However, exclusive e-cigarette use during pregnancy does not reduce rates of adverse 3-month health outcomes or poor birth outcomes. Further research is needed to determine whether these infants achieve age-appropriate developmental milestones in motor, social, and cognitive domains. Our results suggest e-cigarettes are not clinically safer than cigarettes during pregnancy, and physicians should counsel patients on alternative forms of nicotine replacement therapy to support smoking cessation.