
New study sheds light on the safety of MS treatments during pregnancy
A large study of over 3700 pregnancies in people with MS has found that most treatments for MS don’t increase the risk of miscarriage, premature birth or major congenital anomalies.
MS and pregnancy
MS is around three times more common in women than men, and many people are diagnosed at a time when they may be thinking of starting a family. Many disease modifying therapies (DMTs) are now available to manage MS. So it’s important that we understand which treatments are safer during pregnancy.
In this new study, led by Professor Kerstin Hellwig from Ruhr University Bochum in Germany, researchers aimed to understand the effects of specific DMTs during pregnancy in people with MS. This is the largest study of its kind to date.
Pregnancy and MS
If you're living with MS and considering pregnancy, consult your neurologist. They'll be able to guide you on the best treatment options.
The Association of British Neurologists (ABN) has detailed information written for neurologists. It includes two sets of guidelines with recommendations about DMTs and pregnancy.
Read the 2019 ABN pregnancy guidelines
Read the 2022 ABN pregnancy guidelines for ocrelizumab (Ocrevus), ofatumumab and rituximab
For more information, visit our Pregnancy, birth, breastfeeding and MS page.
What did the researchers do?
The team used data from the German MS and Pregnancy Register, which was collected from 2006 to 2023. They studied the pregnancies of 2885 people with MS who used a DMT during pregnancy, and 837 people who didn’t receive any treatment for their MS. They compared the number of miscarriages, infections during pregnancy, premature births, and major congenital anomalies (conditions that are present from birth). They also looked at the babies’ birth weight.
The researchers were able to specifically compare how different treatments affected pregnancy. The rich data in the Registry also allowed the team to rule out factors other than DMTs that could affect pregnancy, making the results more reliable.
The DMTs researchers looked at in the study were:
- beta interferons
- glatiramer acetate
- fumarates (dimethyl fumarate and diroximel fumarate)
- teriflunomide
- S1P modulators (fingolimod, ponesimod)
- alemtuzumab
- natalizumab
- anti-CD20 therapies (rituximab, ocrelizumab, ofatumumab)
- cladribine.
What did they find?
No increased risk of miscarriage, premature birth or major congenital anomalies
The team found no link between DMT use and higher rates of miscarriage, premature birth or major congenital anomalies. However, because only a small number of mothers were taking cladribine, teriflunomide and alemtuzumab, more data is needed to draw any conclusions about the safety of these treatments.
Low birth weight linked to MS
The results showed that babies born to mothers with MS (including those who hadn’t used any DMTs) were more likely to measure smaller in the womb and have a low birth weight. The risk of low birth weight was higher in pregnancies where the mother had used S1P modulators, anti-CD20 therapies, or natalizumab.
Several other studies have also found that people with MS have a higher risk of having a baby with a low birth weight. More research is now needed to understand why this is the case and what the long-term impact of this might be.
Some DMTs are linked with risk of infection
Because DMTs work by changing how the immune system behaves, one concern during pregnancy is the potential risk of infections. This study found that while serious infections during pregnancy were rare overall, they were slightly more common in people treated with fumarates or alemtuzumab. And women who used natalizumab or anti-CD20 antibodies during pregnancy were more likely to need antibiotics.
More research is now needed to understand the risk of infections linked to some DMTs.
What does this mean for people with MS?
This study provides valuable information about the safety of specific DMTs during pregnancy to inform future guidelines. This information can help to empower people with MS and their healthcare providers to make informed decisions about which treatments they should use when planning a family.
This work also highlights the value of using registries to improve our understanding of MS.
If you're pregnant, you could get involved in research like this through the UK MS Pregnancy Register.
Read the full study on pregnancy outcomes in multiple sclerosis on the Lancet website.