“Cigarette smoking in pregnancy is a significant risk factor for maternal and foetal morbidity and mortality,” write the authors of the research paper. “Smoking has long been associated with increased incidence of miscarriage, stillbirth, placental abruption, preterm birth, and low birthweight. Cigarette smoke is a complex heterogeneous mixture of over 4000 compounds, including nicotine, carbon monoxide, carcinogens, and heavy metals.”

Without the combustion or tobacco, vaping presents a fraction of the risk of smoking, according to respected experts – estimated to be at least 95% safer.

McDonnell, Dicker and Regan wanted to see if expectant mothers who vape were jeopardising their infants and focussed a study on a hospital delivering almost 8500 infants per year.

“The use of [electronic cigarettes - EC] 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.”

“The effects of electronic cigarette use in pregnancy are unknown and there are no data on obstetric outcomes among pregnant EC users. Our objective was to examine obstetric outcomes related to EC use in pregnancy. In addition, we sought to determine whether similar socio‐demographic factors would apply in this group of mothers.”

The women were identified via an electronic booking system. The interview is conducted by trained midwives who use a standardised questionnaire to assess smoking habits. It records whether a person has ever smoked, the current self‐reported smoking status, and if she currently vapes.

Exclusive vapers were compared with a group of smokers and non‐smokers who booked and delivered in the same hospital during the study period. Dual-users were considered as a separate group and infant birth weights were compared.

“A total of 449 pregnant users of EC were identified during the study period of 13 months. Of these, 195 women were dual users of EC and cigarettes, a rate of 43.4%, and 254 women reported exclusive EC use at any point in pregnancy. Thirty‐eight women reported that they had never smoked cigarettes, representing a ‘never smokers’ rate of 8.4%. Fourteen women (5.8%) quit EC use between conception and their first booking visit in the early second trimester.”

They write: “Pregnant women who exclusively use electronic cigarettes appear to be a population distinct from those who smoke cigarettes. At the time of this study, e‐cigarette users belong to a higher socio‐economic group than conventional cigarette smokers, a pattern previously seen in the UK which has since attenuated over recent years. They have a higher incidence of planned pregnancy and were more likely to have taken preconceptional folic acid. Over four in ten pregnant users of EC are also smoking cigarettes. These dual users appear to be similar to smokers in both demographics and outcomes.”

The team concluded that the birthweight of infants born to vapers “is similar to that of non‐smokers”, and they said it was “significantly greater” than infants born to cigarette smokers. Dual users who smoke and vape had infants with a birthweight similar to that of smokers.

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