Paternal smoking cessation before pregnancy reduces the risk of spontaneous abortion: a population-based retrospective cohort study
When fathers stopped smoking before conception, miscarriage risk was lower than if they kept smoking.
*Population-based retrospective cohort study; Level 2b (OCEBM).
*Population-based retrospective cohort study; Level 2b (OCEBM).
Citation
Cheng Z, Yang Y, Ding S, et al. Paternal smoking cessation before pregnancy reduces the risk of spontaneous abortion: a population-based retrospective cohort study. Journal of Epidemiology and Community Health. 2026;80:408–415. doi:10.1136/jech-2025-225167.
Background
Smoking by fathers has been linked to pregnancy loss, but the benefit of quitting before conception has been less clear. This study examined whether fathers quitting (or cutting down) before pregnancy lowers miscarriage risk.
Patients
158,986 pregnancies among Chinese women who did not smoke, enrolled in a national pre-pregnancy checkup program (2010–2018) and assessed twice. Exclusions included women who smoked or had missing smoking data, and those lost to follow-up.
Intervention
Father stopped smoking before pregnancy (reported at the second pre-pregnancy visit), or reduced daily cigarettes.
Control
Father continued smoking.
Outcome
Miscarriage before 28 weeks’ pregnancy.
Follow-up Period
Through the subsequent pregnancy outcome after the second pre-pregnancy visit.
Results
| Comparison | Miscarriage rate | Adjusted odds ratio | Number needed to treat (approx.) |
|---|---|---|---|
| Father quit before pregnancy vs continued smoking (primary outcome) | 2.87% vs 3.59% | 0.86 (0.81 to 0.91) | 139 |
| Father reduced 5–9 cigarettes/day vs unchanged/increased | 2.98% vs 3.58% | 0.91 (0.84 to 0.98) | — |
| Father reduced 10–14 cigarettes/day vs unchanged/increased | 3.07% vs 3.58% | 0.88 (0.80 to 0.96) | — |
| Father reduced ≥20 cigarettes/day vs unchanged/increased | 3.31% vs 3.58% | 0.79 (0.62 to 0.99) | — |
| Father reduced 1–4 cigarettes/day vs unchanged/increased | 2.89% vs 3.58% | NS | — |
| Father reduced 15–19 cigarettes/day vs unchanged/increased | 3.59% vs 3.58% | NS | — |
Findings were similar in an additional analysis aimed at reducing hidden confounding (adjusted odds ratio 0.79; 0.76 to 0.82 for quitting vs continuing).
Compared with families where the father never smoked, quitting reduced risk but may not fully eliminate it.
Limitations
Smoking status was self-reported, and the exact time since quitting was unknown. The study included only couples who became pregnant, and very early pregnancy losses may have been missed. As an observational study, residual confounding is possible.
Funding
National Chinese government research grants; funders had no role in analyses.
Clinical Application
In preconception visits, counsel fathers to quit smoking before conception; quitting (and some reductions) modestly lowers miscarriage risk in non-smoking mothers.
Discussion
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In this population-based retrospective cohort study, paternal smoking cessation before pregnancy was associated with lower spontaneous abortion rates (2.87% vs 3.59%; IPW-adjusted OR 0.86). Given the observational design, residual confounding, and self-reported smoking, is this evidence strong enough to change preconception counseling? In this retrospective cohort study, the IPW-adjusted odds ratio for spontaneous abortion with paternal smoking cessation before pregnancy was 0.86. Which interpretation is most appropriate?