title: Parity is associated with a longer time to reach irreversible disability milestones in women with multiple sclerosis.
abstract: BACKGROUND
  Multiple sclerosis (MS) frequently affects women of childbearing age. While short-term effects of pregnancy on MS course are well-known, whether pregnancy may influence long-term disability progression is debated.
  
  
  METHODS
  A two-centre retrospective study to investigate long-term effect of pregnancy on disability was performed in a population of MS women. Survival analyses and multivariate Cox proportional regression models (including early predictors of MS severity and exposure to disease-modifying treatments) were performed to compare time to reach well-established disability milestones in nulliparous women and in those with pregnancies after MS onset ('parous'). Women with pregnancies before MS onset were excluded from analyses as they represent a heterogeneous group.
  
  
  RESULTS
  Data about 445 women (261 nulliparous, 184 'parous') were analysed. A longer time to reach Expanded Disability Status Scale (EDSS) 4.0 and 6.0 was observed in parous women; Cox regression models revealed a lower risk for 'parous' than nulliparous women in reaching EDSS 4.0 and 6.0 (HR = 0.552, p = 0.008 and HR = 0.422, p = 0.012 respectively).
  
  
  CONCLUSIONS
  Our findings suggest that pregnancy after MS onset is associated with a slower long-term disability progression. Whether this represents a biological/immunological effect, or reflects a higher propensity toward childbearing in women with milder disease, it remains uncertain deserving further investigations.
authors.affiliation: MS Centre, Department of Neuroscience, University of Turin & City of Health and Science University Hospital of Turin, Italy.
authors.forename: S
authors.initials: S
authors.lastname: Masera
authors.affiliation: MS Centre, Department of Neuroscience, University of Turin & City of Health and Science University Hospital of Turin, Italy paola.cavalla@unito.it.
authors.forename: P
authors.initials: P
authors.lastname: Cavalla
authors.affiliation: Department of Neurology and Psychiatry, Sapienza University, Rome, Italy.
authors.forename: L
authors.initials: L
authors.lastname: Prosperini
authors.affiliation: MS Centre, Department of Neuroscience, University of Turin & City of Health and Science University Hospital of Turin, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Mattioda
authors.affiliation: Department of Neurology and Psychiatry, Sapienza University, Rome, Italy.
authors.forename: C R
authors.initials: CR
authors.lastname: Mancinelli
authors.affiliation: MS Centre, Department of Neuroscience, University of Turin & City of Health and Science University Hospital of Turin, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Superti
authors.affiliation: MS Centre, Department of Neuroscience, University of Turin & City of Health and Science University Hospital of Turin, Italy.
authors.forename: C
authors.initials: C
authors.lastname: Chiavazza
authors.affiliation: MS Centre, Department of Neuroscience, University of Turin & City of Health and Science University Hospital of Turin, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Vercellino
authors.affiliation: MS Centre, Department of Neuroscience, University of Turin & City of Health and Science University Hospital of Turin, Italy.
authors.forename: L
authors.initials: L
authors.lastname: Pinessi
authors.affiliation: Department of Neurology and Psychiatry, Sapienza University, Rome, Italy.
authors.forename: C
authors.initials: C
authors.lastname: Pozzilli
mesh_terms: D000328:Adult; D017668:Age of Onset; D004185:Disability Evaluation; D006233:Persons with Disabilities; D018450:Disease Progression; D005260:Female; D006801:Humans; D009103:Multiple Sclerosis / Q000175:diagnosis / Q000453:epidemiology* / Q000401:mortality*; D010298:Parity / Q000502:physiology*; D011247:Pregnancy; D012189:Retrospective Studies; D012306:Risk; D016019:Survival Analysis
keywords: Multiple sclerosis; childbearing; disability; disease progression; parenthood; pregnancy