Research: Capricorns favored?

Does birth month influence MS progression? This article says yes, for a data set composed of patients in British Columbia. I haven't read the article, and I'm not a scientists, but it sounds strange to conclude that it is the month of birth that is the operative factor. Interesting stuff, nevertheless. Here's the abstract:

Neuroepidemiology. 2006 Mar 28;26(4):195-198 [Epub ahead of print]

Does the Season or Month of Birth Influence Disease Progression in Multiple Sclerosis?
Tremlett HL, Devonshire VA.
Department of Medicine, University of British Columbia, Vancouver, Canada.

We investigated the influence of season and birth month on sustained progression to Expanded Disability Status Scale 6 (requires a cane) through a database review of 2,319 definite multiple sclerosis (MS) patients followed for a mean 19.3 years, until July 2003 in British Columbia, Canada. The season of birth had a marginal effect on disease progression (p = 0.051), with winter babies exhibiting the slowest progression (p = 0.048). Birth month had a significant effect on progression (p = 0.038), mainly due to those January born having a 40% (95% CI 32.9-47.4) chance of requiring a cane later than those born in other months. There was some evidence to suggest that the gestational period had a small but long-lasting effect on later disease progression in British Columbia, Canada. Copyright (c) 2006 S. Karger AG, Basel.

Link to abstract