Summary of results
E-cigarettes may be more helpful than nicotine patches and do not pose any greater risks to mothers or babies during pregnancy.
The rates of successfully stopping smoking at the end of pregnancy were similar in the two study arms, but some women who quit smoking in the patch group, stopped smoking using e-cigarettes rather than patches. When this was taken into account, women in the e-cigarette group were significantly more successful than those in the patch group (6.8% vs 3.6%).
These quit rates are low because women at the end of their pregnancy or with new-born babies were asked to post their saliva samples to confirm no smoking, and very few did that. Looking at self-reported quit rates (i.e. not confirmed with saliva samples), 19.8% in the e-cigarette group vs 9.7% in the patch group were not smoking at the end of pregnancy.
Adverse events and the health of mothers and babies were similar in the two groups, with one exception. There were fewer low birth-weight babies (weighing under 2.5kg) in the e-cigarette group than in the patch group (9.8% vs 14.8%). This could be because women in the e-cigarette group smoked less.
The full report can be accessed here – https://www.nature.com/articles/s41591-022-01808-0
For study participants reading this summary, thank you for all your help with this very important study.