No adverse pregnancy outcomes linked to e-cigarette use


A comprehensive secondary analysis challenges common concerns by finding no association between the regular use of nicotine patches or e-cigarettes and adverse pregnancy outcomes among smokers seeking to quit.

No adverse pregnancy outcomes linked to e-cigarette use | Image Credit: © leszekglasner - © leszekglasner -

No adverse pregnancy outcomes linked to e-cigarette use | Image Credit: © leszekglasner - © leszekglasner -

The regular use of nicotine patches or e-cigarettes among pregnant mothers is not linked to any adverse pregnancy outcomes, according to recent findings.1

These findings were the result of a secondary analysis of a large randomized controlled trial (RCT) looking at the utilization of both nicotine patches and e-cigarettes among pregnant smokers.2 This research was led by Francesca Pesola, MSc, PhD, from the Wolfson Institute of Population Health at Queen Mary University of London in the UK.

“We present a secondary analysis of this data set that, instead of comparing the randomized groups, compares outcomes in participants who did and did not regularly use these two nicotine products during their pregnancy,” Pesola and colleagues wrote.

Background and Findings

The ‘PREP’ study involved the recruitment of 1140 pregnant individuals known to be daily smokers and reporting the need for assistance in quitting smoking. The participants also had to have no preference for either e-cigarettes or nicotine patches and no current usage.

The outcomes of birth and maternal outcomes in general were assessed in 1095 individuals. Those who decided to have elective termination, withdrew prior to delivery, gave birth outside of study sites with missing information, or gave birth to twins were excluded from the research.

The research team looked at baseline demographic and smoking history data, and saliva samples were collected. Telephone communication was used in weeks 1–4 post-target quit date and at the end of participants’ pregnancies.

Both smoking status and participants’ nicotine product use were looked at by the team. The onset of 4 respiratory symptoms since the beginning treatment were assessed by the investigators at the end of pregnancy, with cotinine analysis being done in 3 participant cohorts to validate self-reported abstinence and reduction in smoking habits.

The investigators monitored subjects’ health statuses and noted any adverse events were in each contact. Research midwives gathered data on birth and maternal outcomes through the use of hospital data.

The research labeled participants reporting no smoking within the prior week at end of pregnancy as 'abstainers,' whereas those reporting smoking or those with missing data were classified by the team as 'smokers.' One was labeled a ‘reducer’ if one reported a 50% reduction in day-to-day cigarette consumption by the end of pregnancy.

Additionally, the investigators defined ‘relapsing’ as having self-reported abstinence at the 4-week mark followed by non-abstinence by the end of pregnancy.

The investigators observed that the participants used e-cigarettes more commonly than nicotine patches (47.3% compared to 21.6%, respectively, P < .001). Among mothers who quit smoking and used e-cigarettes at the end of their pregnancies, the team found there was a 45% salivary cotinine reduction.

Only a single abstainer was shown to have used nicotine patches at the end of pregnancy, and the investigators reported dual users had experienced a 19% cotinine increase. Those seeing a minimum 50% reduction in cigarette use and implementing nicotine products were shown to have a 10% cotinine increase, as opposed to the 9% increase seen in participants who did not.

The research team also reported birth weights among dual users and those who exclusively smoked to be equivalent. They added that abstainers who used either nicotine product ended up having higher birth weights versus smokers and comparable results to abstainers not using nicotine products.

No worse outcomes of pregnancies or greater numbers of adverse events were seen among either abstainers or smokers using nicotine products. Those using e-cigarettes were shown to have had more cough-related improvements and phlegm, controlling for their smoking status.

Lastly, the investigators noted that use of either nicotine patches or e-cigarettes did not contribute to an association with participants’ relapsing.

“We did not detect any risks to pregnancy from (e-cigarettes) nor (nicotine patches) use by smokers trying to quit,” they wrote. “These new findings could alleviate some concerns about use of nicotine-containing products to help pregnant smokers quit, but further studies are needed to verify these results.”

This article was initially published by our sister publication HCP Live.


  1. Pesola F, Smith KM, Phillips-Waller A, Przulj D, Griffiths C, Walton R, et al. Safety of e-cigarettes and nicotine patches as stop-smoking aids in pregnancy: Secondary analysis of the Pregnancy Trial of E-cigarettes and Patches (PREP) randomized controlled trial. Addiction. 2024. doi:10.1111/add.16422
  2. Hajek P, Przulj D, Pesola F, Griffiths C, Walton R, McRobbie H, et al. Electronic cigarettes versus nicotine patches for smoking cessation in pregnancy: a randomized controlled trial. Nat Med. 2022;28:958–964.
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