title: The relapse rate of multiple sclerosis changes during pregnancy: a cohort study.
abstract: OBJECTIVE
  To evaluate the influence of pregnancy and puerperium on the relapse rate of multiple sclerosis (MS).
  
  
  METHODS
  We determined retrospectively the yearly mean relapse rate (MRR) during pregnancies occurring in the course of relapsing-remitting MS. We compared the MRR of pregnancy-time with that of non-pregnancy time by paired t-test. Relative risk (RR) of relapses during the pregnancy-time was also compared with that of non-pregnancy time by chi(2) analysis and 95% confidence intervals.
  
  
  RESULTS
  From a population of 351 women affected by clinically definite MS, only 70 reported pregnancies during their relapsing-remitting phase of MS for a total of 98 pregnancies. Both MRR (P = 0.006) and RR (RR = 0.63, 95% CI = 0.40-0.94) decreased during the three trimesters of pregnancy. RR increased in the first 3 months of puerperium, although this was not statistically significant (RR = 1.36, 95% CI = 0.79-2.20).
  
  
  CONCLUSIONS
  Our study confirms that in MS the relapse rate decreases throughout pregnancy and increases during puerperium. This suggests a complex interplay between hormonal and immune factors.
authors.affiliation: Institute of Neuropsychiatry, University of Palermo, Palermo, Italy.
authors.forename: G
authors.initials: G
authors.lastname: Salemi
authors.forename: G
authors.initials: G
authors.lastname: Callari
authors.forename: M
authors.initials: M
authors.lastname: Gammino
authors.forename: F
authors.initials: F
authors.lastname: Battaglieri
authors.forename: E
authors.initials: E
authors.lastname: Cammarata
authors.forename: G
authors.initials: G
authors.lastname: Cuccia
authors.forename: M
authors.initials: M
authors.lastname: D'Amelio
authors.forename: I
authors.initials: I
authors.lastname: Lupo
authors.forename: P
authors.initials: P
authors.lastname: Ragonese
authors.forename: G
authors.initials: G
authors.lastname: Savettieri
mesh_terms: D000293:Adolescent; D000328:Adult; D015331:Cohort Studies; D015897:Comorbidity; D005260:Female; D006801:Humans; D007558:Italy / Q000453:epidemiology; D008875:Middle Aged; D020529:Multiple Sclerosis, Relapsing-Remitting / Q000453:epidemiology* / Q000503:physiopathology; D011247:Pregnancy; D011248:Pregnancy Complications / Q000453:epidemiology*; D011253:Pregnancy in Adolescence; D012008:Recurrence; D012189:Retrospective Studies; D012307:Risk Factors