Are Disease Modifying Treatments Safe to Use During Pregnancy?

Posted on June 30, 2016

Whether you are planning pregnancy or currently pregnant, some of the most important decisions you make will be regarding medication use during pregnancy. For many women with multiple sclerosis (MS), navigating through different sources of information and deciding on treatment during pregnancy can be difficult. In addition to talking to your providers, you will want to be informed of the latest and most accurate information on medication use during pregnancy. Let’s begin with the basics.

How Do We Know A Medication Is Safe During Pregnancy?

To answer this question, we will want to know the following:

  • How much information is known about my medication when it is used during pregnancy? What is the quality of that information?

The quality and quantity of the information published is very important. For some medications, there may be no human pregnancy reports and information may be limited to animal studies. Other times individual cases of pregnant women are reported, but without being a part of a larger study or group of cases, we cannot draw conclusions based on these types of reports. Since we cannot test the safety of new medications in pregnant women, we rely mostly on observational pregnancy studies. An observational study follows pregnant women who have taken a medication before they knew they were pregnant or who took the medication during pregnancy because their medical condition required ongoing treatment during pregnancy.

  • Have any problems been reported in pregnancy or for the baby, including birth defects, newborn complications, or long-term effects?

Considering all the research studies on a specific medication, we want to know if the information suggests the medication could increase the risk for birth defects, and if a pattern of birth defects has been identified. The key words here are increase and pattern. In every pregnancy regardless of whether she is taking any medication or not, a woman starts out with a 3-5% chance of having a baby with a birth defect; this is called the background risk.1 So a medication that increases the risk of birth defects above the background risk could be concerning. A pattern of birth defects is important because most medications or exposures that affect a developing baby usually cause a distinct pattern of birth defects during pregnancy.

What Are The Current Recommendations For Disease Modifying Treatments During Pregnancy?

Currently there are no official recommendations for treatment of MS during pregnancy because there is not enough research to establish the safety of disease modifying treatments (DMTs). So decisions to use or continue DMT treatment during pregnancy should be made on a case-by-case basis. Sometimes the benefits of using a medication during pregnancy may outweigh the risks; only you and your healthcare provider can determine if that’s the case for you.

What Do We Know About Disease Modifying Treatments For MS During Pregnancy?

There are nearly a dozen DMTs available for the treatment of MS. More is known about older medications called beta-interferons (e.g., Betaseron®, Avonex®, Extavia®, and Rebif®). Studies of pregnancies exposed to a beta-interferon did not suggest an increased chance for birth defects above the background risk.2 In other words, the birth defects seen in these pregnancies were not above what is expected in the general population. In addition, no pattern of birth defects was identified. Because information is still limited we cannot determine the safety of these medications, but to date the information has not suggested a risk for women exposed to beta-interferons very early in pregnancy.

Copaxone® (glatiramer) has not been shown to increase the risk for birth defects; but while the data are reassuring, this is based on limited study of the drug in human pregnancies, so further studies are needed.3 Tysabri®(natalizumab) has also not been associated with an increased risk for birth defects to date, but again information is limited. Also, one study suggested that newborns exposed to Tysabri®may be at risk for complications including reduced red blood cells, platelets, and white blood cells. Red blood cells carry oxygen to the body, platelets play an important role in blood clotting, and white blood cells are a critical part of the immune system that fight off infections. It is expected that more of the medication crosses the placenta later in pregnancy, meaning the effects may be greater during later stages of pregnancy – but more studies are needed to determine the safety of Tysabri® in pregnancy.2

No human pregnancy studies have been published on Tecfidera®(dimethyl fumarate) and Gilenya®(fingolimod), but animal studies suggest possible risk in pregnancy.4Until more information is available, the safety of these treatments in pregnancy is unknown.

Aubagio®(teriflunomide) and Novantrone®(mitoxantrone) have also not been studied in human pregnancy. Animal studies suggest an increased risk of birth defects, so until more data are available it is recommended that women using these medications use appropriate contraception4 to prevent pregnancy, as the risk or safety of these medications in human pregnancies cannot be determined at this time.5,6 Women taking teriflunomide who are planning a pregnancy may receive a separate treatment to reduce the levels of medication in their body before they become pregnant; this treatment may also be used with pregnant women who took teriflunomide before they knew they were pregnant.

How Can We Learn More About MS And Treatments During Pregnancy?

We have a lot to learn about MS during pregnancy as well as the safety of the medications used to treat it. The information available on medications and treatments relies on pregnant and breastfeeding women who are willing to share their experience with others in a confidential manner, so we recommend that all pregnant women participate in a pregnancy registry regardless of their medication use. To better understand medication safety, it is important to compare different groups of pregnant women including those with MS who are not taking medication, those with MS who are taking medication, and those who do not have MS. In short, all pregnant women are needed to help us find answers! Pregnancy registries are strictly observational, meaning that you are not asked to change anything about your normal routine, including the medications you are taking. Contact one or more of the below registries to learn more:

Multiple Sclerosis Pregnancy Registry – Studying all treatments for MS: (877) 311-8972

Aubagio® Pregnancy Registry: (877) 311-8972

Avonex® Pregnancy Registry: (800) 456-2255

Betaseron® Pregnancy Registry: (800) 478-7049

Tysabri® Pregnancy Exposure Registry: (800) 456-2255

Tecfidera® Pregnancy Registry: (800) 456-2255

Gilenya® Pregnancy Registry: (877) 598-7237

Where Can I Get More Information?

We encourage you to speak with your doctor to discuss treatments, options, and what you can expect during pregnancy. For more information about any of the medications discussed above or any other exposures during pregnancy or lactation, you can speak with a MotherToBaby counselor by calling us toll free at (866) 626-6847. Our service is FREE and confidential. If you’d like to know more about current MS and pregnancy registries, please contact one of our MotherToBaby Pregnancy Studies experts toll free at (877) 311-8972.

Elizabeth Salas is the Lead Teratology Information Specialist for MotherToBaby California, a non-profit that provides information to healthcare providers and the general public about medications and more during pregnancy and breastfeeding. She is based at the University of California, San Diego, and is passionate about the work MotherToBaby is doing to promote healthy moms, healthy pregnancies and healthy babies.

MotherToBaby is a service of the international Organization of Teratology Information Specialists (OTIS), a suggested resource by many agencies including the Centers for Disease Control and Prevention (CDC). If you have questions about medications, vaccines, diseases, or other exposures, call MotherToBaby toll-FREE at 866-626-6847 or call the Pregnancy Studies team directly at 877-311-8972. You can also visit to browse a library of fact sheets, as well as visit our Multiple Sclerosis and Pregnancy page at MotherToBaby Pregnancy Studies,



  1. Teratology Primer, Second Edition. Teratology Society. (2010). URL:
  2. REPROTOX® [database online]. Reproductive Toxicology Center. (2014). Updated April 2014 (Interferons). URL:
  3. Tsui, A., & Lee, M. A. (2011). Multiple sclerosis and pregnancy. Current Opinion in Obstetrics and Gynecology, 23(6):435-9. doi: 10.1097/GCO.0b013e32834cef8f.
  4. Clinical Pharmacology [database online]. Tampa, FL: Elsevier/Gold Standard, Inc.; 2014. URL:
  5. Houtchens, M.K., & Kolb, C. M. (2013). Multiple sclerosis and pregnancy: therapeutic considerations. Journal of Neurology, 260(5):1202-14. doi: 10.1007/s00415-012-6653-9.
  6. TERIS® [database online]. Teratogen Information System, University of Washington. (2014). Reviewed 2014 (Teriflunomide). URL:
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