Does pregnancy hasten the onset of secondary progressive MS?

Are  you planning to have extend your family? Learn about MS and pregnancy. #MSBlog #MSResearch

“Wow, wait a moment. The paper below makes the following conclusion ‘pregnancy might in fact accelerate the rate of transition to SPMS’. This is based on the a relative risk of 1.25, in other words females who have been pregnant are 25% more likely to transition to SPMS than those who have not been pregnant. The devil however is in the detail; the 95% confidence intervals are from 0.39 to 3.96. This mean that there is a 95% chance that the real answer is between these two boundaries. In other words pregnancy may actually reduce your risk of becoming secondary progressive by 61% or it may increase your risk by up to 400%. The fact that the confidence interval straddles 1.0 tells you that this result is not significant and hence pregnancy does not increase your risk of becoming secondary progressive. In the same data set pregnancy reduces your chances of irreversible disability by 84% (0.16 (0.03; 0.79)); please note this result is significant because the so called 95% confidence intervals don’t cross 1.0.”

“Could there really be a disconnect between a positive impact on relapses, the acquisition of irreversible disability and the onset of SPMS? I suspect not as several other data sets suggest that pregnancy (single or multiple) has a  positive impact on the progressive phase of the disease.”

“It is interesting to see how much activity is happening in relation to pregnancy and MS. Why? I suspect this is being driven by Pharma who think this will be one of the main differentiators in the DMT market. In particular, the oral DMT market. I have a sense of a deja vu; this is what happened with NABs in the interferon wars. I predict we will see a spate of conferences and satellite symposia dedicated to the topic or pregnancy in MS. Despite being cynical, pregnancy is an important issue and if your are planning to start, or extend, your family you need to be aware of all the relevant issues concerned. For more information please read other posts on this site about pregnancy. You can use the Google search app on the left hand side of the bog; please note this app is only accessible on the web version of the blog.”

Karp et al. Does pregnancy alter the long-term course of multiple sclerosis? Ann Epidemiol. 2014 Jul;24(7):504-508.

PURPOSE: The purpose was to examine the impact of pregnancy on the rates of relapses, progression to irreversible disability, and transition to secondary progressive multiple sclerosis (SPMS) in MSers with RRMS.

METHODS: We retrospectively followed two subcohorts of women with RRMS: pregnant (n = 254) and non-pregnant (n = 423). We obtained data on demographic, lifestyle, and clinical characteristics from patient records.

RESULTS: In the pregnant and non-pregnant subcohorts, respectively, 300 and 787 relapses, 15 and 27 transitions to SPMS, and 11 and 34 progressions to irreversible disability were documented. Adjusted rate ratios (95% confidence intervals) shortly after baseline were 0.67 (0.49; 0.92) for relapses, 0.16 (0.03; 0.79) for irreversible disability, and 1.25 (0.39; 3.96) for SPMS. The corresponding estimates at 5 and 10 years were, respectively, 1.04 (0.72; 1.52), 0.82 (0.36; 1.88), and 2.33 (1.03; 5.26) and 1.62 (0.84; 3.14), 4.14 (0.89; 19.22), and 4.33 (1.10; 16.99).

CONCLUSIONS: Pregnancy likely ameliorates the short-term course of RRMS in terms of the rates of relapses and progression to irreversible disability. Over the long term, it appears to have no material impact on these outcomes, and might in fact accelerate the rate of transition to SPMS.

About the author

Prof G

Professor of Neurology, Barts & The London. MS & Preventive Neurology thinker, blogger, runner, vegetable gardener, husband, father, cook and wine & food lover.


  • So you predict Prof G that the trend will be to give women hormones as DMTs as a new 'flavour of the year'? They should better concentrate on finding something against progression because the fear of disability prevents many MS-ers like me from getting pregnant!

  • Prof G /Mousedoc – would you personally recommend that a lady trying to get pregnant stay on her INFb therapy?

    • No we don't recommend MSers fall pregnant on IFNbeta. You need to stop IFNbeta prior to falling pregnant.

  • As a patient that has one daughter and who wants one more baby in a few years, I'm actually steering clear of the oral drugs until after I'm done having children. I think the risk of bad relapse after stopping treatment is too high, or the need to flush the drug out of my system. I think until I see real data saying it's fine to start and stop, I'll stick to injections (minus tysabri for reasons mentioned above), as much as I hate them.

    I'm happy to hear your analysis about this paper. It seems like the evidence is on the side of a net neutral effect of pregnancy on progression, or inconclusive at best. Hopefully studies will continue to show this for the sale of us parents or want to be parents with ms

By Prof G



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