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Pregnancy and MS: What to Expect Before, During and After

For women with Multiple Sclerosis (MS), the decision to start a family can come with a mix of hope, excitement, and uncertainty. How might MS affect pregnancy - and how might pregnancy affect MS? With growing research and evolving clinical guidance, we now know more than ever about this complex relationship. Neave Smith explores what the science says, offering clarity on key considerations before, during, and after pregnancy.

Multiple Sclerosis (MS) is a chronic autoimmune disease that targets the central nervous system. It occurs when the immune system mistakenly attacks the protective myelin sheath around nerve fibres, disrupting communication between the brain and body. There are several types of MS, each with its own progression pattern:

  • Relapsing-Remitting MS (RRMS): The most common type, marked by flare-ups followed by periods of remission.

  • Secondary Progressive MS (SPMS): Begins as RRMS but gradually worsens over time.

  • Primary Progressive MS (PPMS): Progresses steadily from onset, without relapses or remissions.

  • Progressive-Relapsing MS (PRMS): A rare form that includes continuous progression with intermittent relapses.


For many women with MS, the thought of pregnancy raises important questions. Will MS affect my fertility? Will my symptoms worsen? Are my medications safe to take? The good news is that pregnancy can actually have a protective effect on MS, though the postpartum period requires careful management. Here’s what you need to know.

 


Pregnancy’s Impact on MS: A Temporary Protective Effect


One of the most surprising aspects of MS and pregnancy is that relapse rates decrease, particularly in the second and third trimesters. The landmark Pregnancy in Multiple Sclerosis (PRIMS) study found that relapse rates drop by up to 70% in the third trimester, compared to pre-pregnancy levels (1). The severity of symptoms and degree of disability often impact pregnancy more than the specific MS type. This discovery has since been reinforced by numerous human studies and preclinical research, including work using the experimental autoimmune encephalomyelitis (EAE) animal model of MS (2).  

Why does this happen?

  • Hormonal Changes: The surge in oestrogen and progesterone exerts anti-inflammatory and immunomodulatory effects (3, 4). Studies suggest that high oestrogen levels increase regulatory T cells (Tregs), which suppress autoimmune responses and protect against MS-related inflammation (5).

  • Immune System Shift: Pregnancy naturally induces an immune shift from a Th1-dominant response (pro-inflammatory) to a Th2-dominant response (anti-inflammatory) to prevent foetal rejection (4). This shift temporarily suppresses MS disease activity.



MS and the Placenta: A Natural Barrier


Recent research highlights the protective role of the placenta in MS (6). The placenta produces neuroprotective molecules, including human chorionic gonadotropin (hCG) and corticotropin-releasing hormone (CRH), which have been shown to modulate MS symptoms.

 

💡 Pregnancy can offer a natural “break” from MS relapses - but what happens after the baby arrives?



The Postpartum Period: A Higher Risk of Relapse


While pregnancy can be a period of reduced symptom intensity, the first three to six months postpartum present a higher risk of relapse. The PRIMS study found that relapse rates peak within the first three months postpartum, often exceeding pre-pregnancy levels. 

  • Increased Relapse Risk: After delivery, oestrogen and progesterone levels plummet, and the immune system reactivates, leading to a pro-inflammatory state (7). Women with high disease activity before pregnancy are at greater risk of postpartum relapse.

  • Breastfeeding and MS: It has been shown that women with MS who exclusively breastfed had a lower postpartum relapse rate (8). This may be due to high levels of prolactin, which promotes the repair of myelin sheaths by oligodendrocyte precursors (9). However, findings are mixed, and not all women experience this protective effect.


💡 Key Takeaway: Women at high risk of postpartum relapse should discuss early postpartum treatment options with their neurologist.



Fertility, Pregnancy Outcomes, and MS Medications

Does MS Affect Fertility?


The good news: MS does not impact fertility. Women with MS have the same likelihood of conceiving as those without the condition. However, some disease-modifying therapies (DMTs) may affect ovulation and implantation (10).



Does MS Increase Pregnancy Risks?

Despite common concerns, MS does not increase the risk of miscarriage, congenital abnormalities and gestational hypertension or preeclampsia (11).


However, some MS-related symptoms - fatigue, weakness, and mobility challenges - may impact labour and delivery choices. Women with significant disability (Expanded Disability Status Scale score >6.0) may be more likely to need assisted delivery or C-section (12).

 


MS Medications and Pregnancy


If you’re planning to conceive, reviewing your medication plan is essential. Some DMTs can harm foetal development and must be stopped before pregnancy (13):

🚫 DMTs to Avoid Before Pregnancy

  • Teriflunomide (Aubagio) - Highly teratogenic, remains in the body for up to two years unless actively removed.

  • Fingolimod (Gilenya) - Increases the risk of foetal malformations.

  • Certain monoclonal antibodies (e.g., natalizumab, ocrelizumab, rituximab) - effects vary but some may be used in specific cases.

✅ Safer Options During Pregnancy

  • Glatiramer acetate (Copaxone) – Considered safe for pregnancy.

  • Interferon-beta – Previously avoided, but new evidence suggests it’s not associated with adverse pregnancy outcomes.

 

💡 Key Takeaway: Always discuss medication adjustments with your neurologist before conception to ensure the safest plan for both mother and baby.

 


Long-Term Effects on the Child

Is MS hereditary?


  • If one parent has MS, the risk of the child developing MS is 20-50 times higher than the risk in the general population. However, the absolute risk is only 3-5% (14).

  • The development of MS and the heritability is mainly attributed to the variants in genes that regulate the immune system function.

  • However, the development of MS is not exclusively governed by this one risk.



Could Pregnancy Reduce MS Risk?


Some research suggests that exposure to pregnancy-related hormones might actually lower a child’s risk of developing MS later in life (14). The theory is that these hormones affect foetal immune system programming, leading to a more balanced immune response.

 


Final Thoughts: Planning Ahead is Key


Pregnancy is a unique time for women with MS, offering natural protection from relapses but also presenting postpartum challenges. With careful planning, medication adjustments, and postpartum monitoring, women with MS can have healthy pregnancies and successful recoveries.

 

References:

1. Vukusic, S., & Confavreux, C. (2006). Pregnancy and multiple sclerosis: The children of PRIMS. Clinical Neurology and Neurosurgery, 108(3), 266–270. https://doi.org/10.1016/j.clineuro.2005.11.016

2. Constantinescu, C. S., Farooqi, N., O’Brien, K., & Gran, B. (2011). Experimental autoimmune encephalomyelitis (EAE) as a model for multiple sclerosis (MS). https://doi.org/10.1111/bph.2011.164.issue-4

3. Ramien, C., Yusko, E. C., Engler, J. B., Gamradt, S., Patas, K., Schweingruber, N., Willing, A., Rosenkranz, S. C., Diemert, A., Harrison, A., Vignali, M., Sanders, C., Robins, H. S., Tolosa, E., Heesen, C., Arck, P. C., Scheffold, A., Chan, K., Emerson, R. O., Gold, S. M. (2019). T Cell Repertoire Dynamics during Pregnancy in Multiple Sclerosis. Cell Reports, 29(4), 810-815.e4. https://doi.org/10.1016/j.celrep.2019.09.025

4. Engler, J. B., Heckmann, N. F., Jäger, J., Gold, S. M., & Friese, M. A. (2019). Pregnancy Enables Expansion of Disease-Specific Regulatory T Cells in an Animal Model of Multiple Sclerosis. The Journal of Immunology, 203(7), 1743–1752. https://doi.org/10.4049/jimmunol.1900611

5. Papapavlou, G., Hellberg, S., Raffetseder, J., Brynhildsen, J., Gustafsson, M., Jenmalm, M. C., & Ernerudh, J. (2021). Differential effects of oestradiol and progesterone on human T cell activation in vitro. European Journal of Immunology, 51(10), 2430–2440. https://doi.org/10.1002/eji.202049144

6. R S Goland, S Jozak, W B Warren, I M Conwell, R I Stark, P J Tropper, Elevated levels of umbilical cord plasma corticotropin-releasing hormone in growth-retarded foetuses, The Journal of Clinical Endocrinology & Metabolism, Volume 77, Issue 5, 1 November 1993, Pages 1174–1179, https://doi.org/10.1210/jcem.77.5.8077309

7. Koetzier, S. C., Neuteboom, R. F., Wierenga-Wolf, A. F., Melief, M. J., de Mol, C. L., van Rijswijk, A., Dik, W. A., Broux, B., van der Wal, R., van den Berg, S. A. A., Smolders, J., van Luijn, M. M. (2021). Effector T Helper Cells Are Selectively Controlled During Pregnancy and Related to a Postpartum Relapse in Multiple Sclerosis. Frontiers in Immunology, 12. https://doi.org/10.3389/fimmu.2021.642038

8. Langer-Gould, A., Smith, J. B., Kerstin Hellwig, M., Gonzales, E., Samantha Haraszti, M., Corinna Koebnick, M., & Xiang, A. (2017). Breastfeeding, ovulatory years, and risk of multiple sclerosis.

9. Mouihate, A., & Kalakh, S. (2023). Breastfeeding promotes oligodendrocyte precursor cells division and myelination in the demyelinated corpus callosum. Brain Research, 1821. https://doi.org/10.1016/j.brainres.2023.148584

10. Lamaita, R., Melo, C., Laranjeira, C., Barquero, P., Gomes, J., & Silva-Filho, A. (2021). Multiple sclerosis in pregnancy and its role in female fertility: A systematic review. (Vol. 25, Issue 3, pp. 493–499). https://doi.org/10.5935/1518-0557.20210022

11. Melamed, E., & Lee, M. W. (2020). Multiple Sclerosis and Cancer: The Ying-Yang Effect of Disease Modifying Therapies. In Frontiers in Immunology (Vol. 10). https://doi.org/10.3389/fimmu.2019.02954

12. Van Der Kop, M. L., Pearce, M. S., Dahlgren, L., Synnes, A., Sadovnick, D., Sayao, A. L., & Tremlett, H. (2011). Neonatal and delivery outcomes in women with multiple sclerosis. Annals of Neurology, 70(1), 41–50. https://doi.org/10.1002/ana.22483

13. Bast, N., Dost-Kovalsky, K., Haben, S., Friedmann, N., Witt, L., Oganowski, T., Gold, R., Thiel, S., & Hellwig, K. (2025). Impact of disease-modifying therapies on pregnancy outcomes in multiple sclerosis: a prospective cohort study from the German multiple sclerosis and pregnancy registry. The Lancet Regional Health - Europe, 48.https://doi.org/10.1016/j.lanepe.2024.101137

14. Wang, Y., Wang, J., & Feng, J. (2023). Multiple sclerosis and pregnancy: Pathogenesis, influencing factors, and treatment options. In Autoimmunity Reviews (Vol. 22, Issue 11). Elsevier B.V. https://doi.org/10.1016/j.autrev.2023.103449



This article was written by Neave Smith and edited by Rebecca Pope, with graphics produced by Suzana Sultan. If you enjoyed this article, be the first to be notified about new posts by signing up to become a WiNUK member (top right of this page)! Interested in writing for WiNUK yourself? Contact us through the blog page and the editors will be in touch.


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