Multiple Sclerosis, a progressive autoimmune disease that affects the central nervous system, occurs as a result of demyelination of the sheath that covers the nerve cells. This in turn causes slowing of nerve impulses and a variety of signs and symptoms that come from it. This disease is relevant in pregnancy because of the implications it can have on both the mother and the fetus.
If one parent has the disease, the chances of the child acquiring the disease is approximately 4%. If both parents have MS, then the risk is approximately 20% of the child developing it. (1)
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In a study that took place at the University of British Columbia in Vancouver, Canada, 815 index cases with multiple sclerosis were identified along with 11,345 relatives. The study concluded that first degree relatives of index cases have a 30-50 times higher chance of developing MS compared to the general population. The risk for the general population is 0.1%. (2)
In the PRIMS study or Pregnancy in Multiple Sclerosis (MS) study, 254 women with multiple sclerosis were followed for 2 years. The purpose of this study was to assess how MS would evolve in the postpartum period. The relapse rate postpartum did not vary substantially and was not clinically significant compared to the prepregnancy relapse rate. In this study, they found 3 predictors of relapse rate after pregnancy. These included (1) if the patient had a relapse in the year before pregnancy, (2) if there was an increased rate of relapse during the pregnancy, and the patient’s score on the Expanded Disability Status Scale at the start of the pregnancy. (3) The Expanded Disability Status Scale is a method used to quantify disability in multiple sclerosis. There are eight categories that are assessed. These include: pyramidal, cerebellar, brainstem, sensory, bowel and bladder, visual, cerebral, and other.
Another study reviewed the effects of immunomodulators on pregnancy outcome in women with multiple sclerosis. Two Disease Modifying Therapies (DMTs) were studied. These were glatiramer acetate (GA) and interferon (IFN)-beta1a. The study consisted of 69 pregnant women taking IFN-Beta1a and 31 pregnant women exposed to GA. All women received treatment throughout their first trimester if not longer. The study concluded that there was no pattern of congenital anomalies or increased rate of congenital malformations in the groups receiving the drugs when compared to the control. (4)
References:
1. Houtchens MK. Pregnancy and multiple sclerosis. Semin Neurol. Nov 2007;27(5):434-441.
2. Sadovnick AD, Baird PA, Ward RH. Multiple sclerosis: updated risks for relatives. Am J Med Genet. Mar 1988;29(3):533-541.
3. Vukusic S, Hutchinson M, Hours M, et al. Pregnancy and multiple sclerosis (the PRIMS study): clinical predictors of post-partum relapse. Brain. Jun 2004;127(Pt 6):1353-1360.
4. Weber-Schoendorfer C, Schaefer C. Multiple sclerosis, immunomodulators, and pregnancy outcome: a prospective observational study. Mult Scler. Sep 2009;15(9):1037-1042.
