Electronic Cigarettes and Female Reproduction: A Systematic Review of Experimental and Clinical Evidence

Electronic cigarettes (e-cigarettes) have gained widespread diffusion as a perceived safer alternative to conventional smoking, particularly among women of reproductive age. The present systematic review provides an overview of the current literature on the effects of e-cigarette exposure on female reproductive function, embryonic development, and pregnancy outcomes, with a focus on underlying molecular mechanisms. A systematic literature search was conducted in PubMed, Web of Science, and Google Scholar, and the review was conducted in accordance with the PRISMA 2020 guidelines. A total of 11 studies met the eligibility criteria and were included in the qualitative synthesis, comprising six experimental and five clinical studies. Experimental studies suggest that e-cigarette exposure may impair ovarian function, leading to morphological alterations, disrupted folliculogenesis, and altered steroidogenesis, mainly through oxidative stress, apoptosis, mitochondrial dysfunction, and dysregulation of pathways such as Hippo signaling. Non-nicotine components, including propylene glycol (PG), vegetable glycerin (VG), and flavoring agents, appear to be key contributors. Adverse effects on implantation, embryo development, and placental growth have also been reported in experimental models, although further studies are needed. Clinical evidence remains scarce, suggesting possible associations between e-cigarette smoking and reduced ovarian reserve and fecundability in naturally conceiving women. No conclusive associations have been identified with in vitro fertilization outcomes. Overall, e-cigarette exposure may negatively affect female reproductive function, although the predominance of experimental data and the limited clinical evidence preclude definitive conclusions.