Women’s risk for developing clinically isolated syndrome (CIS) was shown to decrease with increased number of pregnancies
Summary
Women’s risk for developing clinically isolated syndrome, which
often leads to multiple sclerosis, was shown to decrease with
increased number of pregnancies in a comprehensive study
undertaken in Australia. Clinically isolated syndrome (CIS) is a
first neurologic episode caused by inflammation or damage to
nerve fiber-insulating myelin in the brain or spinal cord.
Although the results of this Ausimmune Study need to be
confirmed, the findings encourage further exploration of
potential treatments such as sex hormones, which may mimic
pregnancy’s benefits in women with MS. The sex hormone estriol is
currently in clinical trials to treat women with MS.
[Ponsonby AL, Lucas RM, van der Mei IA, Dear K, Valery
PC, Pender MP, Taylor BV, Kilpatrick TJ, Coulthard A, Chapman C,
Williams D, McMichael AJ, Dwyer T. Neurology. Offspring number,
pregnancy, and risk of a first clinical demyelinating event: The
AusImmune Study. 2012 Mar 7. [Epub ahead of print]
Details
Prior to 1950, most women with MS were advised to avoid pregnancy
because of the belief that it might make their MS worse. Over the
past 40 years, studies in hundreds of women with MS have almost
all reached the opposite conclusion: that pregnancy reduces the
number of MS exacerbations, especially in the second and third
trimesters. The Ausimmune Study was undertaken to investigate
whether increased exposure to sunlight and vitamin D may be
protective against MS in people who had not yet been diagnosed
with MS, but who had experienced a CIS. In the current study, the
team used this unique population to study whether the number of
pregnancies or offspring affects the risk for developing a CIS.
Investigators looked at the records of 282 men and women who had
developed a CIS, and compared the number of children – and in
women, the number of pregnancies – with controls who did not
develop CIS. Women who had one pregnancy were nearly half as
likely to develop CIS, and those with three or more pregnancies
had more than one fourth the risk of developing CIS compared with
controls. Other factors considered – such as sun exposure and
immune-system-related genes associated with MS – did not
otherwise explain these associations. There was no association
between risk of CIS and the number of children in men. In an
accompanying editorial, editorial authors comment that these
findings need to be replicated in other countries to be
validated, and caution that the study does not address whether
pregnancy affects the long-term course of MS or development of
disability. Even with these cautions, the editorial authors say
that because of studies such as this one, there is a compelling
need for research to develop therapeutic approaches that mimic
pregnancy’s benefits in women with MS. Dr. Voskuhl is now leading
a team of investigators at seven medical centers to conduct a
two-year, controlled clinical trial of estriol – a sex hormone
that is increased during pregnancy – added to standard therapy to
treat MS in 150 women with relapsing-remitting MS.
This study provides additional evidence of a link between gender
and autoimmunity.
Source: National MS Society (USA)