title: Cesarean delivery may increase the risk of multiple sclerosis.
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).
  
  
  CONCLUSIONS
  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.
authors: Isfahan Research Committee of Multiple Sclerosis, Multiple Sclerosis Clinic, Al-Zahra hospital, Isfahan University of Medical Sciences, Soffeh Street, Isfahan 81744, Iran. Maghzi@edc.mui.ac.ir
authors: Amir-Hadi
authors: AH
authors: Maghzi
authors: Masoud
authors: M
authors: Etemadifar
authors: Kiyan
authors: K
authors: Heshmat-Ghahdarijani
authors: Safieh
authors: S
authors: Nonahal
authors: Alireza
authors: A
authors: Minagar
authors: Vahab
authors: V
authors: Moradi
mesh_terms: D000328:Adult; D017668:Age of Onset; D002585:Cesarean Section / Q000009:adverse effects*; D005260:Female; D006801:Humans; D016015:Logistic Models; D008297:Male; D009103:Multiple Sclerosis / Q000453:epidemiology / Q000209:etiology*; D016017:Odds Ratio; D012307:Risk Factors; D035781:Siblings