Parental smoking before childbirth and multiple sclerosis onset in their child: a case-control study.

Background: Multiple sclerosis (MS) pathogenesis involves both environmental and genetic factors. Any stage of life, including the prenatal and perinatal years, may be impacted by environmental factors linked to the onset and progression of MS. It is essential to assess these environmental elements in order to avoid the start of illness. However, there is a lack of research on the effects of parental smoking before childbirth.

Objective: This study aimed to investigate the association between MS and parental cigarette consumption before childbirth.

Design and methods: We conducted a case-control study at Sina Hospital, Tehran, Iran, from June 2023 to June 2024. MS diagnosis was confirmed using 2017 revised McDonald's criteria. Experts created a questionnaire to gather information on parental smoking habits, sex, and age. Patients with incomplete questionnaires or parents with MS were not included in the analysis. The control group comprised patients' companions at the Surgical Ward of Sina Hospital. Binary logistic regression was used to estimate the adjusted odds ratios (AOR) and 95% confidence intervals (CI) for MS onset due to paternal and maternal cigarette smoking, adjusting for potential confounders.

Results: A total of 379 MS patients and 379 controls were included in the study. The mean age of the MS patients was 37.97 ± 9.09 years, while the control group had a mean age of 36.13 ± 12.93 years. Our findings indicated that paternal daily cigarette consumption before pregnancy, adjusted for age and sex, increased the risk of MS onset in offspring by 65% (AOR = 1.65, 95% CI: 1.17-2.31, p < 0.004). Furthermore, paternal daily cigarette consumption during maternal pregnancy increased the risk by 71% (AOR = 1.71, 95% CI: 1.21-2.42, p < 0.002). However, no significant association was found between maternal cigarette smoking, either before or during pregnancy, and the onset of MS in offspring.

Conclusions: Paternal cigarette smoking, before and during pregnancy, significantly increased the risk of MS in offspring. These findings highlight the need for further investigation and public awareness, as paternal smoking may represent a preventable risk factor for MS development.