A new study has highlighted significant knowledge gaps on the health outcomes of e-cigarette use during pregnancy

Researchers at the RCSI University of Medicine and Health Sciences and the Coombe Women and Infants University Hospital have published a new study on the outcomes of electronic cigarette use in pregnancy.

The study found that the birth weight of infants born to e-cigarette users is similar to that of non-smokers and significantly greater than babies born to cigarette smokers. Dual users of both cigarettes and e-cigarettes had infants with a birth weight similar to smokers.

However, the study’s authors, RCSI researchers Dr Brendan McDonnell and Dr Carmen Regan, cautioned that further research is needed to establish other health outcomes of e-cigarette use on mothers and babies.

Obstetric outcomes

“Smoking cessation and avoidance of nicotine in its entirety is still the preferable option for pregnant women. However, some women who struggle to stop smoking turn to vaping as a method of harm reduction, and continue to vape in pregnancy,” said Dr McDonnell, the study’s first author, Honorary Clinical Lecturer at RCSI and Bernard Stuart Fellow at the Coombe Women and Infants University Hospital.

“Although our study has found that e-cigarette use appears to have minimal impact on birth weight, the long-term foetal effects of high-dose nicotine such as that received through vaping is unclear. Questions also remain on the effects of the other compounds produced by e-cigarettes, such as aldehydes and nitrosamines on human foetal development.

“Our study highlights that further research is needed to explore other obstetric and neonatal outcomes of vaping. We recommend that all maternity units should record e-cigarette use in pregnant women to deepen our understanding of potential health impacts. Longitudinal studies extending into childhood are needed to measure developmental issues that may arise due to e-cigarette use in pregnancy.”

The study included 218 women with exclusive e-cigarette use and 195 women with dual use of both cigarettes and e-cigarettes attending for antenatal care at the Coombe Women and Infants University Hospital. Infants of e-cigarette users had a mean birth weight of 3,470g, compared to 3,471g for non-smokers and 3,166g for infants of smokers. The study was funded by the Friends of the Coombe charity and by Coombe Women and Infants University Hospital.

The authors wrote: “The use of EC [electronic cigarettes] among pregnant women has increased substantially in recent years. EC are viewed positively by many pregnant women, and research suggests they are perceived as less harmful than cigarettes and useful aids for smoking cessation, despite reservations about safety and nicotine dependence. 

“However, the true risks or benefits of EC use are not well understood. Longitudinal data on safety and the effect on pulmonary and cardiovascular health are lacking, as are data on the foetal effects of EC use. Nicotine is a neuro‐teratogen. It crosses the placenta during pregnancy and is known to bind nicotinic acetylcholine receptors in the foetal brain, altering normal brain development.”

The results showed that in socioeconomic terms, those in the ‘Skilled and non-manual’ category were the most prevalent e-cigarette users, followed by ‘Professional and managerial’ (see Table 1 below).

Table 1

NRT vs e-cigarettes

The researchers also pointed out that users receive a higher dosage of nicotine via e-cigarettes compared to NRT. “Smoking cessation and avoidance of nicotine in its entirety is still the preferable option for pregnant women,” they wrote. 

“However, smoking cessation interventions during pregnancy have limited effectiveness and many women who struggle to achieve cessation turn to EC as a method of harm reduction. This research suggests that exclusive users of EC deliver infants with a birth weight similar to that of non‐smokers. 

“Animal models have suggested a neuro‐teratogenic role of nicotine in foetal brain development. The use of nicotine replacement therapy during pregnancy has not been shown to confer additional risks to offspring; however, the dosage of nicotine received via NRT is less than that received through EC use.”

The research was published recently in BJOG: An International Journal of Obstetrics and Gynaecology and is available at obgyn.onlinelibrary.wiley.com/doi/10.1111/1471-0528.16110.