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Natalizumab Effects on Pregnancy Studied in Women with MS

February 7, 2018

SUMMARY
  • A new study finds that, among 92 pregnancies that involved exposure to treatment with Tysabri® (natalizumab, Biogen), rates of miscarriage and major birth defects were increased more than those in a control group of women with MS whose pregnancies were exposed to no treatment or to interferon betas, but the rates were similar to those in the general population.
  • MS relapses and disease progression were increased in the mothers, and increased risks were associated with a longer “washout period” before becoming pregnant and starting natalizumab later after childbirth.
  • This study adds important information about how medications may affect women with MS who are exposed to treatment during pregnancy, and their babies, but many factors need to be considered as women and their healthcare providers weigh the risks and benefits of treatments and determine the best path forward. Download the Pregnancy, Delivery and Post Partum fact sheet (.pdf) for more information.
  • The team (Emilio Portaccio, MD, Don Carlo Gnocchi Foundation, Florence, Italy) and colleagues report their findings in two papers in Neurology that address fetal (2018;90:1-9) and maternal (2018;90:1-8) risks in MS.
 
DETAILS
Background: In the original clinical trials of the disease-modifying therapies now approved for the treatment of MS, women were required to use contraception during the trials and were discontinued from the trials if they became pregnant. As a result, there was little information on the effects of any of these medications on pregnancy. Since MS primarily affects women of childbearing age who can become pregnant unintentionally, it is extremely important to acquire information about how medications can affect pregnancy and unborn children.
 
These Studies: Investigators collected data on all pregnancies that occurred between 2009 and 2015 in 19 centers in Italy in women treated with natalizumab and compared the records to those of 350 women with MS who were untreated or treated with interferon betas. They looked at the association between treatment and the risks to babies – spontaneous abortion (miscarriage) and major congenital abnormalities (birth defects) – as well as the risks to mothers of relapses and disability progression.
 
Results: Researchers identified 92 pregnancies in 83 women taking natalizumab for relapsing-remitting MS; 75 percent of the pregnancies were exposed to natalizumab for an average of just over a week. Researchers followed up with the women every six months, when they had a relapse and one year after they gave birth.
 
There were 75 live births among the 92 pregnancies. If women were exposed to natalizumab in the first trimester, the rate of miscarriage was 17%; this risk of miscarriage was higher than pregnancies where a mother was untreated or took interferon betas, but the rate is close to the rate for the general population. The risk of major birth defects in the natalizumab group was 3.7%, which was also more than the control group, but similar to the general population. Exposure to both natalizumab and interferons was associated with lower length and weight of babies.
 
The relapse rate during pregnancy was three times higher in women exposed to natalizumab in the first trimester than in women in the control group. A longer “washout period” (with no treatment) before pregnancy was associated with increased risk of relapse during pregnancy. Disease progression occurred in 16% of the women taking natalizumab, compared with 13% in the control group. Progression was reduced in those who resumed natalizumab treatment earlier after childbirth (within one month).
 
The team (Emilio Portaccio, MD, Don Carlo Gnocchi Foundation, Florence, Italy) and colleagues report their findings in two papers in Neurology that address fetal (2018;90:1-9) and maternal (2018;90:1-8) risks in MS.
 
Comment: “This study adds important information about how medications may affect women with MS who are exposed to treatment during pregnancy, and their babies,” says Kathleen Costello, MS, ANP-BC, MSCN, Associate Vice President of Healthcare Access for the National MS Society. “But the decision about taking disease-modifying therapies during pregnancy should not be based on one study. Many factors need to be considered as women and their healthcare providers weigh the risks and benefits of treatment and determine the best path forward.”
 
Read More:
Download the Pregnancy, Delivery and Post Partum fact sheet (.pdf) for more information.
Learn about how MS affects pregnancy and pregnancy affects MS

About Multiple Sclerosis

Multiple sclerosis is an unpredictable, often disabling disease of the central nervous system that disrupts the flow of information within the brain, and between the brain and body. Symptoms range from numbness and tingling to blindness and paralysis. The progress, severity and specific symptoms of MS in any one person cannot yet be predicted, but advances in research and treatment are leading to better understanding and moving us closer to a world free of MS. Most people with MS are diagnosed between the ages of 20 and 50, with at least two to three times more women than men being diagnosed with the disease. MS affects more than 2.3 million people worldwide.

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