Parity Associated with Long-Term Disease Progression in Women with Multiple Sclerosis

Abstract

OBJECTIVE: To investigate the long term effects of pregnancy (parity) on Multiple Sclerosis (MS) disease progression. BACKGROUND: Pregnancy in MS is marked by a decrease in number of relapses with a corresponding rebound in the first months postpartum. Because MS most often occurs during childbearing years, it is of great importance to investigate the long term effects pregnancy has on MS disease course. Results of previous studies on the long term effects of parity on disease progression are controversial. DESIGN/METHODS: All subjects were part of the New York State Multiple Sclerosis Consortium (NYSMSC) registry. 1195 parous and 328 nulliparous women with clinically definite MS age 45 or older were analyzed to determine the time to disease progression. A Cox proportional hazards model was used to examine the effect of parity on time from MS disease onset to Expanded Disability Status Scale (EDSS) 6, while adjusting for confounding factors. RESULTS: Of our sample of 1523 women, the average disease duration was 18.1 years. In the parous group, 23.1% reached EDSS 6, while 26.5% of the nulliparous women reached this disability milestone during follow-up. The Cox survival curves between parous and nulliparous women were significantly different (HR=.68, CI=.53-.87, p=.002), with parous women showing a longer time to reach the disability outcome. CONCLUSIONS: Our results indicate that parous women take a longer time to reach EDSS 6, compared to nulliparous women, suggesting a long term parity benefit. Further studies are necessary to clearly confirm this data as disease specifics may influence a patient to become or not pregnant.