What we’re learning from the UK MS Pregnancy Register?

Multiple sclerosis (MS) often affects people during their child-bearing years meaning people with MS may face complex decisions when planning their pregnancy. To better understand MS and pregnancy, we set up the UK MS Pregnancy Register in 2021. This ongoing study collects information directly from people living with MS who are pregnant and follows them through their pregnancy and postpartum.

What is the aim of the study?

The goal is to gather real-world evidence to help guide healthcare professionals and support people with MS as they make decisions about pregnancy.

What does the study involve?

We ask participants to complete 5 questionnaires during their pregnancy and postpartum periods. We ask participants to complete: a baseline questionnaire when they first sign up and then four follow-up questionnaires at around:

• 15 weeks gestation
• 24 weeks gestation
• 3 months postpartum
• 12 months postpartum

People can sign up at any time during their pregnancy.

Current update: March 2025

This summary includes data from 321 pregnancies.

Pregnancy outcomes:

• The average age of participants was 34 years old and almost half had been pregnant before
• Most had used MS treatments (called disease-modifying therapies or DMTs) for example, natalizumab (Tysabri). Half of participants continued these DMTs into pregnancy, some taking a DMT through their whole pregnancy.
• 2% experienced pregnancy loss (this is very similar to the general population)
• 4% had an MS relapse during or after pregnancy, all were mild to moderate

Postpartum outcomes (data from 48 participants):

• 69% had vaginal births, many required some assistance (e.g., forceps)
• Most caesarean sections (C-sections) were emergency procedures, which is similar to the general population
• Babies were typically born full-term and had average birth weights
• Around 30% of participants reported a complication during delivery, most often heavy bleeding
• A few babies (21%) had a health issue, the most common being cow’s milk allergy
• About half were exclusively breastfeeding
• Some reported that MS had influenced their breastfeeding decisions
• Postpartum depression scores were fairly low and improved over time
• All babies were meeting the expected milestones by 12 months

Conclusions: The findings are reassuring – pregnancy and baby outcomes for people with MS look very similar to those in the general population. Continuing or restarting MS treatment, especially after giving birth, is an important factor in decision-making, particularly around breastfeeding.

The ocrelizumab treatment license has been updated for both the UK and Europe. Given increasing data regarding the safety of ocrelizumab when used close to pregnancy, the regulators have shortened the recommended time between last infusion and trying to conceive to 4 months from the original 12 months. You can read more about our guidance and reasons for this here (Ocrelizumab leaflet).

A further update has also stated that it is safe to breastfeed whilst taking ocrelizumab. This advice is based on evidence from a range of studies, including MINORE and SOPRANINO.

You can read the research here.

New data from the ocrelizumab pregnancy register was published. This study included 3,244 pregnancies; of these 855 women had pregnancies within 3 months of receiving ocrelizumab. It showed that where people received the medication close to pregnancy (within 3 months of conception), there was no increased risk to the pregnancy or baby in terms of pregnancy losses or medical conditions in the baby.

Whilst pregnancy outcomes were available on most people, B cell counts in the babies were only available for a few babies. Whilst most babies were reported to have normal B cell counts, a small number had low counts, most of whom had mothers who had received ocrelizumab early in pregnancy. This is an important area for future study.

You can read the research here.

This study looked at the use of MS symptomatic therapies in and around pregnancy using information from the German MS Register, the largest international pregnancy register. They found that many people with MS considering pregnancy use at least one symptomatic therapy, with almost half using these treatments at some point between pre conception and post partum. Many people choose to stop their treatments for pregnancy purposes, with only about 1 in 10 continuing into pregnancy.

The most common treatments used were antidepressants and pain medications. The numbers using each different medication were small, meaning that precise conclusions about the safety of these treatments couldn’t be established in this study.

However, many of these treatments are used widely across other conditions. Websites like BUMPS (https://www.medicinesinpregnancy.org/) can be really useful when considering how to plan medications around pregnancy and balance risks and benefits.

You can read the research here.

The latest data from the dimethyl fumarate (Tecfidera) pregnancy registry was published. This study looked at pregnancy outcomes in women who were taking dimethyl fumarate at any point during pregnancy from their last period as part of their normal MS care. 397 women with MS provided data for this study. Most people stopped taking Tecfidera when they found out that they were pregnant (at about 5 weeks after their last period). Only 7 people continued the drug into the second trimester, and only 3 into the third trimester.  

Results showed that pregnancy outcomes in terms of pregnancy losses and medical conditions the babies were not different to those seen in the general population. Relapses were not reported in this study, which focused on the safety of medication exposure for the baby.

You can read the research here.

How to approach MS treatments around pregnancy can be daunting. It can feel like there is too much to consider. Many people worry about potential effects of MS treatments during pregnancy on the baby, and weighing this up against the potential effect on MS of potentially stopping treatment.

Many of these issues are covered in a recent paper led by Dr Ruth Dobson, along with a group of international experts. Some of the information in this paper is fairly technical, and it won’t tell you exactly what to do. But it might help you to weigh up some of these options.