<p>Summary of key outcomes and study findings.</p>

Electronic database searches for human and animal studies examining the effects of vaping during pregnancy were conducted in MEDLINE, EMBASE, CINAHL, CENTRAL, PsycInfo, and grey literature, which were completed September 10th, 2025. Data were extracted on study design, population, exposure definitions, outcome domains, and use of biochemical exposure validation. No formal risk-of-bias assessment was undertaken, consistent with scoping review methodology, instead study characteristics were mapped descriptively.</p> <p>Results</p><p>64 studies were included (34 animal, 30 human).

Human studies were predominantly observational and varied in design. Most relied on retrospective self-report without biochemical validation, potentially contributing to contradictory findings. Outcomes were focused mainly on perinatal measures, with maternal outcomes limited to breastfeeding, postpartum depression, and gestational weight gain, and little or no assessment of maternal physiological outcomes such as vascular or autonomic function.

In contrast, animal studies frequently investigated mechanistic outcomes, suggesting potential biological effects across multiple systems including metabolic, respiratory, neurobehavioural, and cardiovascular impairment, with greater severity in nicotine-exposed groups. However, exposure paradigms and species differences limit direct translation to human pregnancy.</p> <p>Conclusion</p><p>The existing evidence base on vaping in pregnancy is characterised by substantial heterogeneity and notable gaps.

In particular, there is a lack of prospective human studies incorporating objective exposure assessment and mechanistic maternal outcomes. Comparative analyses frequently evaluated vaping relative to combustible cigarette smoking. However, substantial variability in exposure classification, comparator groups, and adjustment for confounding limits interpretability.

Animal studies more thoroughly examine mechanistic pathways and multiple organ systems. However physiological differences and unrealistic exposure models limit generalisability to human pregnancy. Overall, the current literature is insufficient to draw firm conclusions regarding risk.

These findings highlight priorities for future research to strengthen the evidence base and improve understanding of the biological effects of vaping during pregnancy.</p></div>