- Design
- Systematic review and meta-analysis of observational studies
- Population
- 22 studies (10 independent samples) of births after in-utero ENDS exposure
- Primary outcome
- Preterm birth, small for gestational age, birthweight
- Effect
- Higher odds of preterm birth vs no exposure; no difference vs cigarette smoking
This systematic review and meta-analysis pooled 22 studies, representing 10 independent samples, that compared births after exclusive exposure to electronic nicotine delivery systems (ENDS) with births after no exposure, nicotine replacement or cigarette smoking.
Compared with no exposure, ENDS use was associated with higher odds of preterm birth (three studies, moderate confidence) and lower birthweight (four studies, moderate confidence), but not with small-for-gestational-age birth. Compared with cigarette smoking, there was no difference in preterm birth (high confidence) or small-for-gestational-age birth. The authors conclude vaping may carry a preterm risk comparable to smoking.
The evidence base is small and observational, and several findings weakened on sensitivity analysis. Still, it undercuts the idea that switching to a vape in pregnancy is a safe harm-reduction step. Where nicotine support is needed, nicotine replacement remains the better-studied option, and complete cessation the goal.
- Ask about vaping separately from smoking at booking — many women do not count it as smoking.
- Do not present switching to a vape as a safe option in pregnancy.
- Aim for complete cessation; offer nicotine replacement where support is needed.
- Record vaping status so the pregnancy can be flagged for preterm and growth surveillance.
Why it matters
Challenges the assumption that moving a pregnant smoker onto a vape reduces the risk to the baby.
Don't overread it
These are observational associations from few studies; they cannot show vaping causes preterm birth.
The statistics, in plain English
Most comparisons rested on three or four studies, and confidence ratings ranged from low to high. "No difference from smoking" means vaping did not look safer — not that smoking is harmless.
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