A recent study has revealed that vaping during pregnancy, even without nicotine, may lead to changes in the structural development of a baby’s skull in the womb.

The study, conducted by researchers at Ohio State University College of Medicine, examined the impact of two commonly used ingredients in e-cigarette liquids—propylene glycol and glycerol—on prenatal development.

The findings suggest that exposure to these substances, even in the absence of nicotine, can potentially affect fetal bone growth.

“Our findings were surprising,” said Dr James Cray, lead researcher and professor at Ohio State University. “The e-cigarettes used in our study did not contain nicotine, yet we observed notable effects on skull development in the models.”

The research, conducted on pregnant mice, involved controlled exposure to different concentrations of propylene glycol and glycerol—liquid components typically found in vaping products. Pregnant mice were divided into three groups: one exposed to filtered air, and two others subjected to vapour containing either a 50:50 or 30:70 ratio of propylene glycol to glycerol.

Over a 20-day gestation period, the mice in the test groups were exposed to one puff of vapour per minute, for four hours a day, five days a week.

The researchers observed that the offspring exposed to the 30:70 concentration mixture had significantly smaller skull measurements compared to the other two groups, indicating potential craniofacial developmental disruptions.

“This raises concerns about the safety of vaping during pregnancy, even when nicotine is not present,” Dr Cray noted. “There is a general perception that nicotine-free vaping is harmless, but our data suggest otherwise.”

While the study was conducted on animals and further research is needed to confirm similar effects in humans, the findings are expected to prompt fresh debate over the regulation and public perception of vaping products, especially among expectant mothers.

E-cigarette use has increased globally in recent years, with many users viewing it as a safer alternative to traditional tobacco smoking. However, health experts have continued to warn about the limited research on the long-term effects of vaping, particularly in vulnerable groups such as pregnant women.

Public health authorities have urged caution, noting that even seemingly benign substances can have unintended consequences on fetal development.

“Pregnancy is a delicate period, and any exposure to foreign substances—nicotine or otherwise—should be approached with extreme caution,” Dr Cray said.