ABSTRACT
BACKGROUND: Prenatal and perinatal factors are believed to contribute to the risk of developing multiple sclerosis (MS). OBJECTIVE: This study was designed to evaluate whether mode of delivery (vaginal versus cesarean section), as a perinatal factor, affects susceptibility to MS. METHODS: MS patients were recruited from the MS registry of Isfahan Multiple Sclerosis Society (IMSS) and were compared with their healthy siblings. Data regarding mode of delivery, birth order, and gestation week of birth were obtained through a specially designed questionnaire. Preterm or post term deliveries were excluded. We used conditional logistic regression statistics and adjusted for gender and birth order. RESULTS: This study included 1349 participants (449 MS patients and 900 controls). Subjects who were born by cesarean section had significant risk of MS (odds ratio, OR = 2.51; 95% confidence interval, CI: 1.43-4.41; p = 0.001). There was significant MS risk for females who were born by cesarean section (OR = 2.69, 95% CI: 1.30-5.58; p = 0.008), but not for males (OR = 2.25, 95% CI: 0.90-5.63; p = 0.082). The mean age at onset was lower in MS patients born by cesarean section (24.58 ± 6.33) compared with that of patients born by vaginal delivery (27.59 ± 7.97; p = 0.041). There was no significant difference between the two groups for birth order (p = 0.417). CONCLUSION: Our results suggest that those born by vaginal delivery are at a lower risk of subsequent MS. These preliminary findings will need to be addressed in a much larger and preferably prospective study.
Subject(s)
Cesarean Section/adverse effects , Multiple Sclerosis/etiology , Adult , Age of Onset , Female , Humans , Logistic Models , Male , Multiple Sclerosis/epidemiology , Odds Ratio , Risk Factors , SiblingsABSTRACT
AIMS: We aimed to study the smoking habits of multiple sclerosis (MS) patients and their healthy siblings in Isfahan province in Iran. METHODS: MS patients registered with the Isfahan MS society database were compared to their healthy siblings who served as controls. Data regarding the smoking habits of patients and their siblings were collected using a specially designed questionnaire. Conditional logistic regression was adopted to analyze the association of smoking with the risk of MS, adjusting for age and sex. RESULTS: There were 1,606 participants with 516 cases and 1,090 controls. After adjustments for age and sex, subjects who were ever-smokers had a significant risk of developing MS [odds ratio (OR) 2.67; 95% confidence interval (CI) 1.70-4.21; p <0.001]. Past smokers (OR 8.83; 95% CI 3.98-19.60; p < 0.001) and current smokers (OR 1.84; 95% CI 1.10-3.10; p = 0.021) had a significant risk for developing MS. Disease progression (current expanded disability status scale/disease duration) was not different between smokers and nonsmokers (0.54 ± 0.42 vs. 0.49 ± 0.48; p = 0.61). CONCLUSION: Using a sibling pair method our data confirm the association between smoking and MS. A degree of confounding due to overmatching between siblings was unavoidable, but any bias would be conservative and should have lessened the effect of smoking.