The influence of pregnancy on disability from multiple sclerosis: a population-based study in Middlesex County, Ontario.

We analyzed the effect of pregnancy on long-term disability resulting from multiple sclerosis in 185 women ascertained through a retrospective population-based survey of MS in Middlesex County, Ontario, Canada. There was no association between disability and total number of term pregnancies, timing of pregnancy relative to onset of MS, or either onset or worsening of MS in relation to a pregnancy. The mean number of pregnancies both before and after onset of MS was no different among groups stratified according to disability. This study addresses some of the difficulties inherent in studying the effect of pregnancy on disability resulting from MS.