Objective Electronic cigarette use has increased significantly in recent years, with users perceiving it to be healthier, cleaner and more cost effective than cigarette smoking. However significant concern remains over their use in pregnancy due to a lack of data on safety and on maternal and fetal outcomes. In addition, nicotine crosses the placenta and has a direct effect on both the fetus and the placental vasculature and has been labelled a neuro-teratogen for its effects on fetal brain development.

Study Design We conducted a prospective cohort study of pregnant users of electronic cigarettes attending a large urban maternity hospital delivering over 8500 infants per year. Women were identified via the electronic booking system at first visit to the hospital. Maternal and neonatal outcomes were collected after delivery and compared to a contemporaneous group of smokers and non-smokers.

Results 129 women booked with a history of exclusive electronic cigarette use during the study period. Of these, 85 had a livebirth, 39 remain pregnant, and 1 patient had a second trimester miscarriage. Infants born to users of electronic cigarettes had a mean birth weight of 3482g (+/- 549g), which was similar to non-smokers (3471g +/-504g, p=0.75) and significantly greater than that of smokers (3166g +/- 502g, p=0.001). Mean gestation at delivery was similar in electronic cigarette users, non-smokers, and smokers (39.3, 39.8, and 39.3 weeks respectively). The mean birth centile of electronic cigarette users was similar to non-smokers (51st centile vs. 47th centile, p=0.28) and significantly greater than that of smokers (27th centile, p=0.00001). There were no cases of serious maternal morbidity. Delivery outcomes including need for induction, mode of delivery, perineal trauma and post-partum hemorrhage were all similar to those of non-smokers, as were admission rates to the SCBU/NICU. There were no cases of neonatal respiratory distress syndrome.

Conclusion The use of electronic cigarettes in pregnancy is not associated with low birth weight or preterm delivery. Both maternal and neonatal outcomes appear to be similar to non-smokers. To our knowledge, this is the first prospective study on the relationship between electronic cigarette use and maternal and fetal outcomes.