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Men who swapped cigarettes for vaping during IVF saw better sperm motility and fewer miscarriages, but experts warn that vaping isn’t risk-free for hopeful parents.

Study: Impact of conventional cigarette and electronic cigarette use on sperm quality and IVF/ICSI outcomes. Image Credit: New Africa / Shutterstock

In a recent study published in the journal Scientific Reports, researchers evaluated whether exclusive Electronic cigarette (e-cigarette) use alters semen quality and live-birth outcomes compared with traditional cigarette smoking in couples undergoing in vitro fertilization (IVF).

The study did not include a non-smoking control group, so results specifically compare E-cigarette users to conventional cigarette smokers, not to non-smokers.

Background

Despite decades of anti-smoking campaigns, about one-third of men of reproductive age still smoke conventional cigarettes. Meanwhile, sleek E-cigarettes that heat flavored nicotine liquids have surged in popularity and are marketed as safer. Traditional smoking is firmly linked to lower sperm count, reduced motility, and higher miscarriage rates, but the reproductive impact of electronic aerosols that are rich in metals and aldehydes remains poorly defined.

Couples investing in costly IVF worry whether switching from smoke to vapor truly protects fertility or merely changes the risk profile. Comparative evidence, particularly within assisted reproductive technology, is limited, and further research is needed to clarify these uncertainties.

About the study

Medical records from one infertility clinic were reviewed for 296 couples who underwent IVF or intracytoplasmic sperm injection between May 2022 and January 2024. Male partners had exclusively smoked either conventional cigarettes or E-cigarettes for at least six months and provided semen after two to seven days of abstinence.

The study enrolled couples in which the woman’s infertility was attributed to tubal disease, polycystic ovary syndrome, thyroid dysfunction, hyperprolactinemia, or a prior failed intrauterine insemination. Every female participant was a confirmed nonsmoker.

Researchers excluded participants with advanced maternal age, endometriosis, adenomyosis, poor ovarian response, recurrent pregnancy loss, congenital genitourinary anomalies, severe male-factor infertility, or any history of switching between cigarette types. Only the first or second embryo transfer cycles were included to avoid confounding from recurrent implantation failure.

They then performed standard semen analysis, calculated body mass index, assayed serum follicle-stimulating hormone (FSH), luteinizing hormone (LH), testosterone, prolactin, anti-Müllerian hormone (AMH), and sex hormone-binding globulin (SHBG), and proceeded with controlled ovarian stimulation under a gonadotropin-releasing hormone (GnRH) antagonist protocol, retrieving oocytes 36 hours after a recombinant human chorionic gonadotropin (rhCG) trigger.

All embryos were cryopreserved as blastocysts and transferred in frozen-thawed cycles. Outcomes included categories of pregnancy, miscarriage, and live birth, plus semen parameters. Chi-square and independent t-tests were used to compare groups, and logistic regression identified live-birth predictors at a p-value of ≤ 0.05.

Study results

Male partners in the conventional-cigarette (n = 151) and E-cigarette (n = 145) cohorts shared comparable body metrics and most hormonal parameters, but three laboratory values diverged. Traditional smokers exhibited higher serum prolactin (13.84 ± 5.97 ng/mL vs 13.02 ± 4.80 ng/mL; p = 0.029) and greater sperm concentration (81.55 ± 57.19 × 10⁶/mL vs 71.78 ± 44.40 × 10⁶/mL; p = 0.007), whereas progressive motility was higher among vapers (48.91 ± 11.75 % vs 48.15 ± 13.29 %; p = 0.014); semen volume, leukocyte count, and strict morphology did not differ (p > 0.10).

Female partners in both cohorts were similar in age and ovarian-reserve indices. Their body mass index, however, was modestly higher when the male partner smoked conventional cigarettes (23.38 ± 4.29 kg/m²) compared to vaping (22.16 ± 3.47 kg/m²; p = 0.017). Controlled ovarian stimulation proceeded uniformly: stimulation lasted 9.6 ± 1.5 days with a total gonadotropin dose of 2,385.68 ± 1,047.71 IU in smokers and 2,338.45 ± 898.18 IU in vapers, producing comparable oocytes retrieved (19.19 ± 10.29 vs 19.76 ± 10.67) and two-pronuclear embryos (11.23 ± 7.00 vs 11.28 ± 6.75; all p > 0.38).

Pregnancy endpoints diverged only after ultrasound confirmation. Biochemical pregnancy, clinical pregnancy, ongoing pregnancy, and biochemical miscarriage rates were statistically indistinguishable (p ≥ 0.16). Male partners who vaped rather than smoked were associated with a drop in ultrasound-confirmed miscarriages from 36.3% to 12%, a roughly two-thirds relative reduction (p < 0.001). Concurrently, live-birth rates increased from 41.1% to 55.9%, representing a 15-percentage-point absolute rise (p = 0.011).

Multivariable logistic regression for all 296 couples revealed two independent live-birth predictors: every 1 mIU/mL increase in male serum FSH raised the odds by 19% (adjusted odds ratio 1.19, 95% confidence interval 1.06-1.34; p = 0.004), whereas each additional two-pronuclear embryo reduced the odds (adjusted odds ratio 0.19, 95% confidence interval 0.05-0.71; p = 0.013). However, this latter result is biologically counterintuitive and contradicts the direction seen in univariate analysis; it likely reflects either a statistical artifact or residual confounding and should be interpreted with caution.

Smoking modality, sperm motility, and paternal or maternal body mass index did not retain independent significance once these laboratory factors were taken into account.

The authors note that, although differences in semen parameters and live birth outcomes were observed between cigarette types, key predictors of live birth (such as FSH and 2PN embryo count) did not differ significantly between groups.

Conclusions

To summarize, E-cigarette use by male partners undergoing IVF appears less detrimental to reproductive success than continued conventional smoking. Although semen concentration was marginally lower, progressive motility was higher and prolactin lower among vapers, translating into fewer clinical miscarriages and a fifteen-point gain in live-birth rate.

Importantly, cigarette type did not override established predictors such as FSH level or embryo count, underscoring that vaping is no guarantee of success.

Crucially, the authors emphasize that these findings should not be interpreted as an endorsement of E-cigarette use, since E-cigarettes still pose potential health risks and their long-term impact on reproductive health is not fully understood.

The retrospective design, reliance on self-reported data, lack of information on dietary factors, unmeasured heavy metal exposure, and unaccounted variability in E-cigarette devices all limit causal conclusions and generalizability. Further research, including direct comparisons with non-smokers and more detailed toxicological assessment, is needed to clarify the reproductive risks of E-cigarettes and guide fertility counseling.

These findings highlight how lifestyle choices can still influence assisted reproduction outcomes and support counseling men to abandon combustible tobacco while pursuing parenthood more safely.