title: Is season of birth associated with multiple sclerosis?
abstract: OBJECTIVE
  To compare the monthly distribution of multiple sclerosis (MS) patients' births with that of the Sicilian population.
  
  
  BACKGROUND
  Studies on the association between season of birth and risk of MS are scanty and controversial.
  
  
  METHODS
  Archives of the Institute of Neuropsychiatry of the Universities of Palermo and Catania were searched up to 1995 for definite MS patients (McDonald & Halliday criteria). The monthly distribution of MS patients' births (N= 965) was compared with that of the Sicilian population (N= 5,608,307).
  
  
  RESULTS
  The distribution of births among MS patients compared with the general population was not different when tested by the chi2 statistic (P> 0.25). The Hewitt's non-parametric test for seasonality showed an excess of births between June and November among MS patients (P=0.004).
  
  
  CONCLUSIONS
  A different pattern of MS patients' births is observed in Sicily and in Northern countries.
authors.affiliation: Institute of Neuropsychiatry, University of Palermo, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Salemi
authors.forename: P
authors.initials: P
authors.lastname: Ragonese
authors.forename: P
authors.initials: P
authors.lastname: Aridon
authors.forename: A
authors.initials: A
authors.lastname: Reggio
authors.forename: A
authors.initials: A
authors.lastname: Nicoletti
authors.forename: D
authors.initials: D
authors.lastname: Buffa
authors.forename: S
authors.initials: S
authors.lastname: Conte
authors.forename: G
authors.initials: G
authors.lastname: Savettieri
mesh_terms: D000367:Age Factors; D005260:Female; D006801:Humans; D015994:Incidence; D009103:Multiple Sclerosis / Q000453:epidemiology* / Q000209:etiology*; D011247:Pregnancy; D012307:Risk Factors; D012621:Seasons; D012802:Sicily / Q000453:epidemiology