title: Cesarean section and offspring's risk of multiple sclerosis: a Danish nationwide cohort study.
abstract: BACKGROUND
  Apart from a recent study reporting a 2- to 3-fold increased risk of multiple sclerosis (MS) among women and men who were delivered by Cesarean section (C-section), little attention has been given to the possible association between mode of delivery and the risk of MS.
  
  
  OBJECTIVE
  We studied the association between C-section and risk of MS, in a cohort of 1.7 million Danes born from 1973 to 2005.
  
  
  METHODS
  Information on C-section and MS was obtained from the Danish Medical Birth Register and the Danish MS Register, respectively. The association between C-section and MS was evaluated by means of MS incidence rate ratios (RR) with 95% confidence intervals (CI) obtained in log-linear Poisson regression analyses.
  
  
  RESULTS
  There were 930 cases of MS in the study cohort, of whom 80 (9%) were delivered by C-section. Overall, we found there was no significant association between C-section and risk of MS (RR = 1.17; 0.92-1.46). Analyses stratified by sex revealed no unusual risk of MS for women (RR = 1.08: 0.80-1.42) nor men (RR = 1.37: 0.91-1.98). A supplementary sibling-matched Cox regression analysis likewise suggested there was no excess risk of MS in persons delivered by C-section (HR = 1.03; 0.63-1.69).
  
  
  CONCLUSIONS
  Mode of delivery appears to be unimportant in relation to MS development in the offspring.
authors: Department of Epidemiology Research, Statens Serum Institut, Copenhagen, Denmark.
authors: Nete M
authors: NM
authors: Nielsen
authors: Peter
authors: P
authors: Bager
authors: Egon
authors: E
authors: Stenager
authors: Bo V
authors: BV
authors: Pedersen
authors: Nils
authors: N
authors: Koch-Henriksen
authors: Henrik
authors: H
authors: Hjalgrim
authors: Morten
authors: M
authors: Frisch
mesh_terms: D002585:Cesarean Section / Q000009:adverse effects*; D015331:Cohort Studies; D003718:Denmark / Q000453:epidemiology; D005260:Female; D006801:Humans; D008297:Male; D009103:Multiple Sclerosis / Q000453:epidemiology*; D011247:Pregnancy; D016016:Proportional Hazards Models; D012307:Risk Factors
keywords: C-section; Multiple sclerosis; disease risk; immunology; mode of delivery; offspring