Foetal mouth movements: Effects of nicotine.

Aim: To assess whether foetal mouth movement frequency changes across gestation and whether there are differences between cigarette and e-cigarette exposure conditions in comparison to a non-exposed group of foetuses.

Method: Pregnant women underwent 4-dimensional (4D) foetal ultrasound scans at 32 weeks (106 scans) and 36 weeks of gestational age (87 scans) at James Cook University Hospital, UK. The 4D scans were coded using the Fetal Observable Movement System (FOMS). Measures of maternal smoking status, stress, depression, anxiety, attachment and time of scan were also collected. There were four exposure groups: non-smokers, light smokers (<10 per day), heavy smokers (11-20 per day) and e-cigarette users.

Results: No significant differences in relative frequency of mouth movements between the exposure groups at 32- and 36 weeks of gestational age were found. Foetal mouth movements declined from 32 to 36 weeks of gestation for non-exposed and e-cigarette-exposed foetuses.

Conclusion: Due to variability in foetal behaviour, examining mouth movements alone may not be the most appropriate method for assessing group differences. However, in line with other research, mouth movement frequency declined between 32- and 36 weeks of gestational age. A combination of foetal behavioural assessments is needed to assess the effects of cigarette and e-cigarette exposure on foetal neurobehavioural development.