The relapse rate of multiple sclerosis changes during pregnancy: a cohort study

Acta Neurol Scand. 2004 Jul;110(1):23-6. doi: 10.1111/j.1600-0404.2004.00270.x.


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).

Conclusion: 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.

MeSH terms

  • Adolescent
  • Adult
  • Cohort Studies
  • Comorbidity
  • Female
  • Humans
  • Italy / epidemiology
  • Middle Aged
  • Multiple Sclerosis, Relapsing-Remitting / epidemiology*
  • Multiple Sclerosis, Relapsing-Remitting / physiopathology
  • Pregnancy
  • Pregnancy Complications / epidemiology*
  • Pregnancy in Adolescence
  • Recurrence
  • Retrospective Studies
  • Risk Factors