UK consensus on pregnancy in multiple sclerosis: An update to ‘Association of British Neurologists’ guidance

Abstract

Background:

The first Association of British Neurologists (ABN) UK multiple sclerosis (MS) pregnancy guidelines were published in 2019. Along with new disease-modifying treatments, significant new data have since become available, resulting in label changes and recognition of class effects. Alongside this, there has been increasing recognition of the importance of family planning considerations in treatment paradigms in MS.

Methods:

We set out to update the ABN UK MS Pregnancy guidance with a systematic literature search, with updated guidance informed by multidisciplinary input from across neurology, obstetric medicine, pharmacy and specialist nurses.

Guidance:

Key updates include consideration of disease-modifying therapy mechanism and durability of action when discussing treatment approaches around pregnancy, alongside considering the impact of treatment withdrawal on relapses during pregnancy and in the postpartum period. Monoclonal antibody transfer into breast milk is generally accepted to be low, and so treatment during lactation can be considered. Active discussion around vaccination strategies during pregnancy and of the neonate is required, with vaccines generally considered safe. With active treatment strategies that take these factors into account, women can be reassured regarding disease control during pregnancy.

Conclusion:

Data sources remain limited, and further dedicated real-world studies that capture the full range of outcomes required to inform risk–benefit discussions are needed. These require collaboration and infrastructure to support the delivery of high-quality care to all women with MS considering pregnancy.

Keywords

Multiple sclerosis pregnancy disease-modifying therapy

Introduction

The first Association of British Neurologists (ABN) UK multiple sclerosis (MS) pregnancy guidelines were published in 2019.¹ Since then, a number of new disease-modifying treatments have become widely available, including both monoclonal antibody-based treatments (ofatumumab, ublituximab) and oral therapies (ponesimod, ozanimod, siponimod, cladribine). In addition, significant new data have become available, including new safety data, advances in our understanding of the importance of class effects, nuance around the use of monoclonal antibodies in and around pregnancy and lactation studies. As a result, label changes for ocrelizumab and recognition of class effects in terms of breast milk transfer for anti-CD20 agents have been approved by regulatory authorities. Approaches to MS management have increasingly considered family planning, reflected in the 2023 update to the NHS England disease-modifying treatment (DMT) algorithm² and 2024 ABN DMT guidance.³ Recommendations for the use of assisted reproduction technologies have been positively influenced by recent studies.⁴ Public involvement has highlighted both the crucial nature of previous guidance for people with MS considering family planning and the need for updated consensus guidance that enables the provision of high-quality, evidence-informed care across the United Kingdom.

This update aims to facilitate informed discussions between MS healthcare professionals and people living with MS about pregnancy and family planning. We hope that the use of this guidance will improve the delivery of personalised care that enables patients and their treating clinicians to balance maternal and foetal/neonatal health.

Methods

This guidance was developed to build on previous work.¹ A systematic literature search (performed by G.M., supported by H.F. and R.D., initially performed in April 2025 and most recently updated in September 2025 to allow important additions to be included in the final draft) identified research publications relevant to guidance development. Reviews were used to provide context and approaches from leaders in the field. A provisional set of recommendations was circulated to the authorship group. Consensus was reached through iteration and discussion, and a draft set of guidance was circulated to stakeholders, including the ABN, MS Society, MS Trust, London MS Pharmacist network and Neurology Academy for review. Feedback was considered and incorporated along with the updated literature review, and final guidance was developed.

As part of the development of this updated guidance, we considered sex and gender terminology. Pregnancy research has historically used terms relating to biological sex and gender interchangeably, although they are distinct. We use the terms ‘woman/women’ in this guidance in reference to biological sex and in line with the evidence underpinning our advice. However, we note that not all people with MS who are planning to or have become pregnant identify as women. This guidance applies across gender terminology, and the terms used should not be considered exclusionary. Neurology and obstetric services and delivery of care must be appropriate, inclusive and sensitive to the needs of all people accessing care.

Consensus guidance

Unless specifically stated or superseded, recommendations within our previous guidance still stand. Figure 1 summarises general approaches to pregnancy planning in MS.

Pre-pregnancy counselling

Key updates

Changes in the natural history of MS, the impact of DMT withdrawal for those on immunosequestering DMT, the possibility to continue some DMT safely through pregnancy and the potential durability of induction therapies and immunodepleting DMT should all be considered when discussing treatment approaches in the context of family planning.

Where assisted reproduction technologies are required as part of family planning, women with MS can be reassured regarding their safety in terms of relapse risk based on recent large studies.

Recommendations

Having MS does not automatically mean a pregnancy should be judged as high risk. Personalised approaches to pregnancy planning should consider both the clinical history and likely MS disease activity during pregnancy and postpartum, along with the potential impact of treatment withdrawal. MS relapse rates have fallen over time,⁵ likely relating to more effective treatments alongside a wider diagnostic spectrum. The potential for sustained efficacy of specific DMTs in the context of potential treatment suspension should be acknowledged when discussing treatment approaches around pregnancy. Potential differences between immunosequestering DMT (such as natalizumab and sphingosine-1-phosphate (S1P) modulators) versus immunodepleting (such as anti-CD20) and immune reconstitution therapies (such as cladribine and alemtuzumab) should be acknowledged. Recent studies have highlighted that DMT withdrawal (especially immunosequestering DMT) may result in a return or even rebound of inflammatory disease activity not suppressed by pregnancy.^6,7 If required, relapses may be treated with steroids during pregnancy.

Assisted reproduction technologies (ARTs) have not been found to increase relapse rates in recent large studies, particularly where DMTs are continued during ART procedures.^8–10 Both gonadotropin-releasing hormone agonist and antagonist protocols can be used in people with MS, as evidenced by these data.⁴ Shared decision-making involving people with MS and their families, fertility specialists leading ART and the MS team is paramount to ensure timely access to ART and effective MS treatment.

Symptomatic therapies also require consideration. In general, it is important to weigh up the individual risk of stopping or switching medication alongside the potential harm to the unborn baby from continuing any medication. This is a complex decision, potentially requiring multi-professional input, and should be discussed as part of a preconception pregnancy plan. The lowest effective dose of medication for the shortest period needed to maintain symptom control should be prescribed, which may mean restarting or commencing some medications at a later stage in pregnancy.^11,12

Key updates

During pregnancy, women should be advised to receive seasonal vaccinations for influenza and COVID (if available). In addition, pertussis vaccination (administered as part of the diphtheria, tetanus, pertussis vaccine) should be offered in the second trimester, and respiratory syncytial virus vaccination in the third trimester in line with national guidance for all pregnant women to protect the neonate in the first few months of life. This guidance is relevant regardless of prior or current DMT exposure. These vaccinations provide potential protection for mother and/or neonate via passive immunity.

Management during pregnancy

Recommendations

During pregnancy, women should be advised to receive seasonal vaccinations for influenza and COVID (if available) to provide protection during pregnancy. In addition, pertussis vaccination (administered as part of the diphtheria, tetanus, pertussis vaccine) should be offered in the second trimester and respiratory syncytial virus vaccination in the third trimester to protect the neonate in the first few months of life, regardless of prior or current DMT exposure. The pneumococcal polysaccharide vaccine is generally considered to be safe in pregnancy. These vaccinations provide potential protection for both mother and neonate via passive immunity.

In general, steroids used for the treatment of MS relapse are safe in pregnancy. Women with MS who have a disabling relapse during pregnancy should be offered intravenous or high-dose oral methylprednisolone, regardless of trimester. Any underlying infection, such as a urinary tract infection, should be excluded. For very severe relapses that do not respond to corticosteroids, plasma exchange can be considered.

MRI is not contraindicated at any time during pregnancy; however, gadolinium contrast media should be avoided where possible.¹³ In the context of clinical stability during pregnancy, routine imaging is not necessarily required. However, in the postpartum period, where therapeutic lag may be a consideration and disease activity is more likely to occur,¹⁴ re-baseline imaging should be considered.

Delivery and anaesthetic options

Recommendations

Having MS should not influence the mode of delivery or analgesia/anaesthesia unless there is significant disability. Women should have the full range of delivery options available based on their individual situation and wider obstetric risk. There is insufficient evidence to recommend routine umbilical cord blood collection and banking for women with MS for future MS-related treatments, for example, stem cell therapies.

Postpartum advice

Key updates

Consideration needs to be given to therapeutic lag when initiating DMT postpartum. The optimal time to recommence therapy remains a key unanswered question.

Women with MS should be encouraged to breastfeed alongside resumption of breastfeeding-compatible DMT, where breastfeeding is in line with their wishes. Women with active disease pre-pregnancy should be particularly encouraged and supported to consider restarting DMT alongside breastfeeding. In general, monoclonal antibodies do not pass into breast milk, with drug-specific data emerging. Breastfeeding remains safe while taking methylprednisolone.

If contrast MRI is required in the postpartum period, there is no evidence of risk to the baby/child from contrast administration while breastfeeding.

Recommendations

Where certain DMTs are stopped before or during pregnancy, therapeutic lag needs to be considered in terms of DMT choice and timing when restarting postpartum.¹⁵ The optimal time to recommence each DMT to prevent postpartum relapses remains a key unanswered question.

Women with MS should be encouraged and supported to breastfeed where in line with their wishes, alongside resumption of breastfeeding-compatible DMT. Women with active disease pre-pregnancy should be particularly supported to consider restarting DMT alongside breastfeeding. Only very low levels of monoclonal antibodies pass into breast milk and will be degraded by stomach acid, meaning that infant exposure is negligible.¹⁶ IgG concentrations are higher in colostrum, which is the first, highly nutritious milk produced for up to a week postpartum.¹⁷ This is of relevance to restarting monoclonal antibodies postpartum where pregnancy exposure has not occurred, as administration to breastfeeding mothers who are in the first few postpartum days may lead to inadvertent neonatal exposure. Studies examining specific monoclonal antibodies¹⁸ and extrapolations regarding class effect can provide reassurance to women considering restarting DMT alongside breastfeeding.

There is no evidence to support immunoglobulin or regular methylprednisolone to prevent relapses in the postpartum period. There is no indication to stop breastfeeding if methylprednisolone is required to treat a postpartum relapse, other than if relapse-associated disability prevents safe breastfeeding.¹⁹ Where intravenous methylprednisolone is used, serum concentrations peak in the first few hours following infusion. If transfer to the breastfeeding neonate is a concern, then feeding just before methylprednisolone administration and delaying the next feed as long as possible may minimise transfer. In general, there is no need to discard milk or fully suspend breastfeeding. If contrast MRI is required in the postpartum period, women who wish to continue breastfeeding can do so.²⁰

Disease-modifying therapy specific statements

Key considerations for disease-modifying therapies around pregnancy and breastfeeding in people with multiple sclerosis are summarised in Figure 2.

Injectable therapies

Key updates: Platform injectable therapies

Interferon beta and glatiramer acetate are now licensed for use during pregnancy and breastfeeding internationally.

Interferon beta (Avonex, Betaferon, Extavia, Plegridy, Rebif) and glatiramer acetate (Copaxone, Brabio)

Recommendations

Both interferon beta (IFN-B) and glatiramer acetate (GA) are licensed for use in pregnancy and during lactation internationally. A small study demonstrated minimal levels of pegylated IFN-B in the breast milk of treated mothers;²¹ observational studies have demonstrated safe outcomes during breastfeeding.^22,23

Monoclonal antibodies

Key updates: monoclonal antibodies

Women taking natalizumab should be counselled regarding the well-documented safety profile during pregnancy along with the risk of return of disease activity on pausing/cessation. Switching to an alternative high efficacy DMT should be considered before conception; however, switching should not usually occur during pregnancy. Where natalizumab is used during pregnancy, there are potential implications for rotavirus vaccination of the neonate, as natalizumab can block lymphocyte trafficking across the gut. No adverse events have been reported in this context; this should be discussed on a case-by-case basis with women. Women should be reassured and encouraged to arrange that they and their infants receive all other vaccinations. Extended dosing of natalizumab does not appear to adversely affect the relapse rate during pregnancy.

A branded biosimilar natalizumab (Tyruko) is available; there is no reason to believe that this drug will have any differential effect in pregnancy compared with the originator product.

Anti-CD20 therapy can safely be continued until a positive pregnancy test. Use of ocrelizumab and rituximab before pregnancy has been associated with durable disease control into the postpartum period. Administration of anti-CD20s during pregnancy is not normally recommended in MS. Anti-CD20 therapy can be restarted after the first few days postpartum. Rotavirus vaccination should only be delayed where anti-CD20s are administered during pregnancy and infants have depleted CD19 B-cell counts.

Natalizumab (Tysabri, Tyruko)

A branded biosimilar natalizumab (Tyruko) is now available, but there are no pregnancy data available yet. There is no reason to believe that this drug will have any differential effect on pregnancy compared with the original product; however, pharmacovigilance is essential for reporting of exposed pregnancies.

If women are considering or currently receiving natalizumab while trying to conceive, the risks and benefits of stopping versus continuing treatment during pregnancy should be discussed, ideally before conception.²⁴ This discussion should include the following:

There is a risk of rebound, that is, a severe increase in relapse rate, associated with stopping natalizumab.²⁵ The effect of pregnancy on relapse rate may be insufficient to control MS disease activity and prevent rebound if natalizumab is stopped.^6,24

There is no specific pattern of birth defects associated with natalizumab treatment during pregnancy.^26,27

Natalizumab exposure during late pregnancy has been associated with mild to moderate reversible neonatal anaemia and thrombocytopenia. Consideration should be given to performing a third-trimester ultrasound to assess for potential anaemia and to checking the neonatal full blood count to guide further monitoring.

Consideration of switching to an alternative high efficacy DMT with a durable mechanism of action, such as anti-CD20 therapy, should be considered before conception as part of pregnancy planning; however, switching should not usually occur during pregnancy. Switching will not be a suitable approach for all women with MS.

In common with most monoclonal antibodies, natalizumab does not cross the placenta during the first trimester, but it is increasingly actively transported during the second and third trimesters. To minimise foetal exposure, the frequency of natalizumab (intravenous infusions or subcutaneous) should be reduced to 6–8 weekly, with the last dose given usually no later than approximately 34 weeks gestation. Natalizumab should be restarted postpartum within 6–8 weeks of the last dose, irrespective of breastfeeding, to avoid rebound disease activity. Extended dosing of natalizumab does not appear to adversely affect relapse rate during pregnancy.^26,28,29 Cases of disease reactivation with extended interval subcutaneous natalizumab have been reported; however, it must be noted that these are in the context of prolonged suspension (>100 days) in the third trimester of pregnancy.³⁰

Routine MR brain imaging monitoring for progressive multifocal leukoencephalopathy should continue during pregnancy.

Natalizumab crosses into breast milk in small amounts with some increase over time.³¹ However, oral bioavailability is negligible. There are significant benefits of breastfeeding, and women who wish to breastfeed while taking natalizumab should be supported to do so.^31–33

When natalizumab is used during pregnancy, neonates should be assumed to be exposed. This has potential implications for rotavirus vaccination, as natalizumab can block lymphocyte trafficking across the gut, and rotavirus vaccination is a live attenuated oral vaccine. No adverse events have been reported in this context. However, this should be discussed on a case-by-case basis with women. Women should be reassured and encouraged to arrange all other vaccinations for their infants, as natalizumab is not peripherally immunosuppressive.

Anti-CD20 agents: Ocrelizumab (Ocrevus IV and SC preparations), ofatumumab (Kesimpta), ublituximab (Briumvi), rituximab (off-label indication, widely used internationally)

No data exist for ublituximab, and limited data exist for ofatumumab; however, class effects can be used to guide treatment strategies. There is no evidence that anti-CD20 therapy impacts fertility in either sex. A large-scale study found no increased risk of adverse pregnancy outcomes, congenital malformations or miscarriage with ocrelizumab use until shortly after conception.³⁴ Placental transfer and foetal exposure of ocrelizumab have been shown to be minimal when treatment is administered shortly before conception.³⁵ The use of ocrelizumab and rituximab before pregnancy has been associated with durable disease control into the postpartum period.³⁶ Ocrelizumab treatment until the point of conception does not affect infant B-cell levels. Treatment during pregnancy has been associated with low infant B-cell levels and so should generally be avoided.³⁷ Given existing data, we advise continuation of anti-CD20 therapy until a positive pregnancy test.

We recommend restarting anti-CD20 treatment early in the postpartum period. There is no requirement to prescribe split doses for women established on intravenous ocrelizumab or ublituximab before pregnancy, as the first dose splitting in these medications relates to tolerability rather than pharmacokinetics. Ofatumumab re-loading may be indicated to enable rapid return to therapeutic levels. Very low levels of ocrelizumab are detected in the breast milk of treated mothers.³⁸ In line with class effects and product licences, women with MS should be advised that it is safe to breastfeed while taking all anti-CD20 monoclonal antibodies with no meaningful breastmilk transfer following the first few postpartum days.

Anti-CD20 exposure via administration during pregnancy has implications for rotavirus and Bacillus Calmette-Guérin (BCG) vaccinations, the two live vaccines potentially administered in the first year of life. B-cell depletion may decrease the efficacy of live attenuated vaccines alongside potentially increasing the risk of adverse events. In the rare instances where infants are exposed via anti-CD20 dosing during pregnancy, infant CD19 B-cell levels should be measured before vaccine administration and, if low, immunisation should be delayed until counts have recovered. Non-live vaccines should be administered as per schedule, as, although a reduced response is possible, this remains preferable to non-vaccination.

Oral therapies

Key updates: oral therapies

There is no evidence that dimethyl fumarate exposure early in pregnancy leads to increased congenital malformation or miscarriage rates. Women with MS can continue dimethyl fumarate until pregnancy is confirmed, based on reassuring evidence regarding the continuation of treatment until the point of the first positive pregnancy test. Continuation through pregnancy is not usually advised but may be considered as part of shared decision-making.

No pregnancy data exist on diroximel fumarate; there is no reason to believe this will have differential effect compared with dimethyl fumarate.

The active metabolite of dimethyl fumarate, monomethylfumarate, is detected only in low levels in breast milk. A small study has suggested no harm to the infant from exposure to dimethyl fumarate through breastfeeding; women should be counselled on a case-by-case basis, considering their individual preferences.

Data suggest an increased risk of congenital malformation with first-trimester fingolimod therapy. Women should be advised to use effective contraception while taking any S1P modulator, and alternative treatments should be discussed.

Dimethyl fumarate (Tecfidera) and diroximel fumarate (Vumerity)

No pregnancy data exist on diroximel fumarate. While there is no reason to believe that this drug will have any differential effect on pregnancy compared with dimethyl fumarate, as both involve the same active metabolite, adequate pharmacovigilance is essential.

There is no evidence in human studies of dimethyl fumarate resulting in reduced fertility or increased congenital malformation or miscarriage rates.^39,40 Women with MS can continue dimethyl fumarate until pregnancy is confirmed but should then stop treatment. Evidence is reassuring regarding continuation of treatment until the point of first positive pregnancy test, with the short half-life meaning that this approach minimises exposure in pregnancy.⁴⁰ In addition, there is no evidence of a significant risk of disease rebound with this approach.

The active metabolite of dimethyl fumarate, monomethylfumarate, is detected only in low levels in breast milk.^41,42 While a small study has suggested no harm to the infant during breastfeeding,⁴³ women should be counselled regarding the lack of data when deciding approaches to treatment during breastfeeding.

Teriflunomide (Aubagio)

Evidence regarding teriflunomide exposure in pregnancy is extremely limited. Teriflunomide is teratogenic in animals at equivalent doses to those given to humans, and we advise caution in prescribing this to women of childbearing age, although real-world evidence to date has been reassuring.^44,45 There is no evidence of teratogenicity caused by men taking teriflunomide or that teriflunomide adversely affects male fertility or damages sperm.

Women who have an unplanned pregnancy while taking teriflunomide should undergo the accelerated elimination procedure as soon as possible. Pregnancies in women on teriflunomide should be treated as high risk with referral to an obstetrician for consideration of a foetal medicine scan.

Women should not take teriflunomide while they are breastfeeding as animal data suggest it likely passes into breast milk and may be absorbed by the neonate.

Sphingosine-1-phosphate receptor modulators: fingolimod (Gilenya), siponimod (Mayzent), ozanimod (Zeposia), ponesimod (Ponvory)

Data suggest an increased risk of congenital malformation with first-trimester fingolimod treatment, totalling an incidence of 9% in one study, although data were underpowered for statistical significance.^46,47 A small study suggests no adverse outcomes for foetuses exposed to ozanimod during the first trimester of pregnancy.⁴⁸ No pregnancy data exist for siponimod or ponesimod. Women with MS should be advised to use effective contraception while taking any S1P receptor modulator, and alternative treatments should be discussed and recommended as part of pregnancy planning.

Women with MS planning to become pregnant should be advised of the respective washout periods for S1P receptor modulators.^49–52 Women with MS should be advised that the risk of rebound relapse after fingolimod discontinuation is high, with potential for severe relapse and disability accrual.^53,54 This remains a concern for other S1P receptor modulators, although different pharmacokinetic profiles likely impact this risk. Proactive switching to different DMT with proven safety in pregnancy should be prioritised in women taking S1P considering pregnancy. Pregnancies in women on S1P receptor modulators should be treated as high risk with referral to an obstetrician for consideration of a foetal medicine scan.

As S1P receptor modulators are small molecules with high potential for transfer into breast milk and subsequent gastrointestinal absorption by the neonate, women should not take S1P receptor modulator treatment while breastfeeding.

Immune reconstitution therapies

Key updates: Immune reconstitution therapies

The UK licence for cladribine has recently been extended to include anyone with active RRMS. While the limited amount of available pregnancy data is reassuring for those with unintended pregnancies, pregnancy should be avoided for 6 months following cladribine in women and for 3 months following cladribine in men. Where women with MS can have a full treatment course in advance of conception, cladribine could represent an effective means for a drug administration-free pregnancy.

Women with MS undergoing haematopoietic stem cell transplantation (HSCT) should be advised that this can directly affect fertility and may cause infertility. Women and men with MS undergoing HSCT should be offered fertility preservation through oocyte or sperm cryopreservation.

Cladribine (Mavenclad)

The UK licence for cladribine has recently been extended to include anyone with active relapsing remitting MS. Despite teratogenic concerns with concurrent treatment, cladribine can have a role in pregnancy planning. Where women with MS can have a full treatment course in advance of conception, cladribine could represent an effective means for a drug-free pregnancy.

Cladribine is excreted in human breast milk in low quantities, and this significantly reduces within 24 hours of the final tablet.⁵⁵ Breastfeeding is contraindicated during treatment with cladribine and for 1 week after the last dose. In patients who require blood transfusion, irradiation of cellular blood components is recommended before administration in line with the summary of product characteristics (SmPC).

Alemtuzumab (Lemtrada)

Serum concentrations of alemtuzumab are low or undetectable approximately 30 days after a course of treatment.⁵⁶ Women should use effective contraception for 4 months following a course of treatment with alemtuzumab.

Women are at risk of autoimmune adverse events in the years following alemtuzumab treatment. Autoimmune events peak at year 3, and risk subsequently declines thereafter.⁵⁷ These may occur during pregnancy and affect both the mother and foetus (for instance, neonatal thyrotoxicosis, maternal hypothyroidism with impact on foetal development). Routine blood and urine safety monitoring should be continued through pregnancy.

Haematopoietic stem cell transplantation

Women with MS undergoing haematopoietic stem cell transplantation (HSCT) should be advised that this can directly affect fertility and may cause infertility. HSCT can also cause premature menopause.⁵⁸ Women and men with MS undergoing HSCT should be offered fertility preservation through oocyte or sperm cryopreservation.

Available evidence suggests no adverse pregnancy outcomes in cancer patients who have previously undergone HSCT, although birth rates are significantly lower than those in the general population, and many require ART for conception.^59,60

Breastfeeding should be avoided during HSCT treatment.

Conclusions

As knowledge around the management of MS around pregnancy has increased, neurologists and people living with MS now have meaningful options to suppress relapses at this important stage of life. The success of active and effective treatment paradigms during this critical time period, along with the potential negative impact of pausing/withdrawal of non-depleting immunotherapies, has been highlighted in recent data.⁷ This guidance provides current advice; future updates will be required as new data emerge, with formal review required within 3 years.

Despite recent improvements in management, important questions remain. Generating safety data regarding use of medications in and around pregnancy has been slow, and data sets are often limited, collecting only part of the data needed to fully inform risk–benefit discussions. Currently unanswered questions include identifying those people who are at the highest risk of relapse during pregnancy aside from the risk associated with DMT withdrawal, evaluating the optimal time to restart DMT to minimise the risk of postpartum relapse, balancing potential risks from potential exposure during breastfeeding, and informing vaccination strategies in potentially exposed neonates.

Data to answer these questions must originate from real-world studies, such as population-level pregnancy research, and must additionally be communicated to both healthcare teams and people living with MS. The importance of national studies to address these questions has been shown by studies originating from Germany and France.^23,61 Within the United Kingdom, initiatives such as the website www.pregnancy.ms and the UK MS Pregnancy Register have an important role to play in enabling women to make informed decisions and collecting data on as many UK MS pregnancies as possible, so we can start to answer questions of importance to patients and those treating them.

Figure 1.

General approaches to pregnancy planning and considerations in people with multiple sclerosis.

Figure 2.

Key considerations for disease modifying therapies around pregnancy and breastfeeding in people with multiple sclerosis.

Footnotes

Declaration of Conflicting Interests

The authors declared the following potential conflicts of interest with respect to the research, authorship and/or publication of this article: Ger Mullan has received speaking fees from Merck and Novartis; these have been donated in full to MS Trust with receipts available on request. Helen L. Ford has received research support from the Health Technology Assessment Programme (NIHR), EME Programme, the UK MS Society and the Horne Family Foundation. She has taken part in advisory boards and consultancy for Merck, Novartis and Roche and received support for attending educational meetings from Novartis and Roche. Paula Blackall has nothing to disclose. Denisse Bongol has received support for conference attendance from Novartis and Roche. Nicola Bonham has nothing to disclose. Peter Brex has received sponsorship to attend educational meetings or honoraria for talks or attending advisory board meetings for Merck, Novartis, Roche and Janssen. Natasha Hoyle has received honoraria for advisory boards and/or educational activities from Merck, Roche, UCB and Sandoz. Katy Murray has received funding from Biogen, Merck, Neuraxpharm, Novartis and Roche covering consultancy work, talks and support to attend educational meetings. She is an independent assessor in a Roche-sponsored MOG-AD trial. Catherine Nelson-Piercy has received speakers fees from UCB and Sanofi-Aventis and consultancy fees from UCB. Owen R. Pearson has received honoraria and travel expenses from Biogen, Bayer, Genzyme, Merck, Novartis, Roche, Sanofi and Teva and served on advisory boards/acted as a speaker for Biogen, Celgene, Janssen, Merck, Neuraxpharm, Novartis, Roche and Sanofi. David Rog has received consulting and/or speaking fees in the last 5 years from Biogen, Janssen, Merck, Neuraxpharm, Novartis, Roche, Sanofi, Hikma and Teva. Research support paid to an institutional research fund from Actelion, Biogen, GW Pharma, MedDay, Merck, Mitsubishi, Novartis, Sanofi Genzyme, Teva and TG Therapeutics. Paarul Prinja has received speaking fees from Ferring and Bayer UK. Ruth Dobson has received research support from Merck, Biogen and Celgene, consultancy fees from F. Hoffmann-La Roche Ltd, Novartis, Sandoz and Biogen and honoraria from Biogen, F. Hoffmann-La Roche Ltd, Sanofi Genzyme, Sandoz, Merck, Novartis, Janssen and Eisai.

Funding

The authors received no financial support for the research, authorship and/or publication of this article.

ORCID iDs

Ger Mullan

Helen L Ford

Denisse Bongol

Owen R Pearson

Ruth Dobson

Data Availability Statement

Data sharing is not applicable to this article as no data sets were generated or analysed during this study.

References

Dobson

Dassan

Roberts

, et al. UK consensus on pregnancy in multiple sclerosis: ‘Association of British Neurologists’ guidelines. Pract Neurol 2019; 19: 106–114.

NHS England. Treatment algorithm for multiple sclerosis disease-modifying therapies. London: NHS England, 2023.

Rashid

Ciccarelli

Leary

, et al. Using disease-modifying treatments in multiple sclerosis: Association of British Neurologists (ABN) 2024 guidance. Practical Neurology 2025; 25: 18–24.

Mullan

Hughes

Rog

, et al. Assisted reproduction technology in multiple sclerosis. Pract Neurol 2025; 25: 300–302.

Papathanasiou

Hibbert

Tallantyre

, et al. Real-world annualized relapse rates from contemporary multiple sclerosis clinics in the UK: A retrospective multicentre cohort study. Neurol Sci 2023; 44: 3629–3635.

Yeh

Widyastuti

Van der Walt

, et al. Natalizumab, fingolimod and dimethyl fumarate use and pregnancy-related relapse and disability in women with multiple sclerosis. Neurology 2021; 96: e2989–e3002.

Gavoille

Rollot

Casey

, et al. Therapeutic management during pregnancy and relapse risk in women with multiple sclerosis. JAMA Neurol 2025; 82: 994–1003.

Mainguy

Tillaut

Degremont

, et al. Assessing the risk of relapse requiring corticosteroids after in vitro fertilization in women with Multiple Sclerosis. Neurology 2022; 99: e1916–e1925.

Graham

Bakkensen

Anderson

, et al. Inflammatory activity after diverse fertility treatments: A multicenter analysis in the modern multiple sclerosis treatment era. Neurol Neuroimmunol Neuroinflamm 2023; 10: e0200106.

10.

Mainguy

Casey

Vukusic

, et al. Assessing the risk of relapse after in vitro fertilization in women with multiple sclerosis. Neurol: Neuroimmunol Neuroinflam 2025; 12: 1–14.

11.

Iyer

Wiles

Ismail

, et al. Developing evidence-based guidelines for the safety of symptomatic drugs in multiple sclerosis during pregnancy and breastfeeding: A systematic review and Delphi consensus. Mult Scler 2023; 29: 395–406.

12.

Witt

Haben

Dost-Kovalsky

, et al. Impact of symptomatic multiple sclerosis therapy on pregnancy outcome. Mult Scler 2024; 30: 1775–1787.

13.

Ray

Vermeulen

Bharatha

, et al. Association between MRI exposure during pregnancy and fetal and childhood outcomes. JAMA 2016; 316: 952–961.

14.

Anderson

Krysko

Rutatangwa

, et al. Clinical and radiologic disease activity in pregnancy and postpartum in MS. Neurol Neuroimmunol Neuroinflamm 2021; 8: e959.

15.

Haben

Ciplea

Tokic

, et al. Early postpartum treatment strategies and early postpartum relapses in women with active multiple sclerosis. J Neurol Neurosurg Psychiatry 2024; 95: 151–157.

16.

Keizer

Huitema

ADR

Schellens

JHM

, et al. Clinical pharmacokinetics of therapeutic monoclonal antibodies. Clin Pharmac 2010; 49: 493–507.

17.

Rodríguez-Camejo

Puyol

Fazio

, et al. Antibody profile of colostrum and the effect of processing in human milk banks: Implications in immunoregulatory properties. J Hum Lact 2018; 34: 137–147.

18.

Bove

Hellwig

Pasquarelli

, et al. Ocrelizumab during pregnancy and lactation: Rationale and design of the MINORE and SOPRANINO studies in women with MS and their infants. Mult Scler Relat Disord 2022; 64: 103963.

19.

Boz

Terzi

Zengin Karahan

, et al. Safety of IV pulse methylprednisolone therapy during breastfeeding in patients with multiple sclerosis. Mult Scler J 2018; 24: 1205–1211.

20.

The Royal College of Radiologists. RCR and SoR statement on patients who are breastfeeding who require a CT or MRI with contrast, https://www.rcr.ac.uk/news-policy/latest-updates/rcr-and-sor-statement-on-patients-who-are-breastfeeding-who-require-a-ct-or-mri-with-contrast/ (2022, accessed 14 July 2025).

21.

Houtchens

Mahlanza

Ciplea

, et al. Peginterferon beta-1a concentrations in breast milk of lactating multiple sclerosis patients. Mult Scler Rel Dis 2022; 60: 103700.

22.

Klehmet

Begus-Nahrmann

Taipale

, et al. Impact of interferon beta exposure on birth outcome and child development – Results from the post-authorisation safety study PRIMA. Mult Scler Rel Dis 2023; 77: 104844.

23.

Bast

Dost-Kovalsky

Haben

, et al. Impact of disease-modifying therapies on pregnancy outcomes in multiple sclerosis: A prospective cohort study from the German multiple sclerosis and pregnancy registry. Lancet Reg Health Eur 2025; 48: 101137.

24.

Hellwig

Tokic

Thiel

, et al. Multiple sclerosis disease activity and disability following discontinuation of natalizumab for pregnancy. JAMA Netw Open 2022; 5: e2144750.

25.

Portaccio

Moiola

Martinelli

, et al. Pregnancy decision-making in women with multiple sclerosis treated with natalizumab: II: Maternal risks. Neurology 2018; 90: e832–e839.

26.

Thiel

Litvin

Haben

, et al. Disease activity and neonatal outcomes after exposure to natalizumab throughout pregnancy. J Neurol Neurosurg Psychiatry 2024; 95: 561–570.

27.

Friend

Richman

Bloomgren

, et al. Evaluation of pregnancy outcomes from the Tysabri^® (natalizumab) pregnancy exposure registry: A global, observational, follow-up study. BMC Neurol 2016; 16: 1–9.

28.

Toorop

van Lierop

ZYGJ

Gelissen

LMY

, et al. Prospective trial of natalizumab personalised extended interval dosing by therapeutic drug monitoring in relapsing-remitting multiple sclerosis (NEXT-MS). J Neurol Neurosurg Psychiat 2024; 95: 392–400.

29.

Rabea

Belal

Nourelden

, et al. A systematic review and meta-analysis of extended interval dosing (EID) vs. standard-interval dosing (SID) of Natalizumab for multiple sclerosis patients (P8-3.005). Neurology 2023; 100: 3533.

30.

Ricigliano

VAG

Landi

Boudot de la Motte

, et al. Risk of postpartum disease activity with subcutaneous versus intravenous Natalizumab in pregnant women with multiple sclerosis. Mult Scler Relat Disord 2026; 109: 107086.

31.

Baker

Cooper

Kessler

, et al. Transfer of natalizumab into breast milk in a mother with multiple sclerosis. J Hum Lact 2015; 31: 233–236.

32.

LaHue

Anderson

Krysko

, et al. Transfer of monoclonal antibodies into breastmilk in neurologic and non-neurologic diseases. Neurol Neuroimmunol Neuroinflamm 2020; 7: e769.

33.

Proschmann

Thomas

Thiel

, et al. Natalizumab during pregnancy and lactation. Mult Scler 2018; 24: 1627–1634.

34.

Vukusic

Bove

Dobson

, et al. Pregnancy and infant outcomes in women with multiple sclerosis treated with ocrelizumab. Neurol Neuroimmunol Neuroinflamm 2025; 12: e0200349.

35.

Hellwig

Bove

Dobson

, et al. B cell levels and placental transfer in infants potentially exposed to ocrelizumab during pregnancy: Analysis of the Phase IV MINORE study, https://medically.roche.com/global/en/neuroscience/ectrims-2024/medical-material/ECTRIMS-2024-poster-hellwig-b-cell-levels-and-placental-transfer-in-infants-pdf.html (2024, accessed 5 May 2025).

36.

Anderson

Rowles

Poole

, et al. Anti-CD20 monoclonal antibody therapy in postpartum women with neurological conditions. Ann Clin Transl Neurol 2023; 10: 2053–2064.

37.

Schwake

Steinle

Thiel

, et al. Neonatal B-cell levels and infant health in newborns potentially exposed to anti-CD20 monoclonal antibodies during pregnancy or lactation. Neurol Neuroimmunol Neuroinflamm 2024; 11: e200264.

38.

Bove

Oreja-Guevara

Hellwig

, et al. B-cell levels and breastmilk transfer in infants of lactating women with multiple sclerosis treated with ocrelizumab: Primary results of the prospective, multicentre, open-label, phase IV study SOPRANINO. Abstract 0102, Mult Scler 2025; 31: 3 supplement.

39.

Landi

Bartolomeo

Bovis

, et al. Maternal and fetal outcomes in an Italian multicentric cohort of women with multiple sclerosis exposed to dimethyl fumarate during pregnancy. Mult Scler 2024; 30: 1503–1513.

40.

Hellwig

Rog

McGuigan

, et al. Final analysis of 379 pregnancy outcomes after exposure to dimethyl fumarate in a prospective international registry. Mult Scler 2024; 30: 209–215.

41.

Van Neste

Nauwelaerts

Ceulemans

, et al. Very low monomethyl fumarate exposure via human milk: A case report – A contribution from the ConcePTION project. Front Publ Health 2024; 12: 1–8.

42.

Ciplea

Datta

Rewers-Felkins

, et al. Dimethyl fumarate transfer into human milk. Ther Adv Neurol Disord 2020; 13: 968414.

43.

Borriello

Ianniello

Efficacy, safety and tolerability of dimethylfumarate during pregnancy and breastfeeding. Mult Scler Relat Disord 2022; 67: 103949.

44.

Vukusic

Coyle

Jurgensen

, et al. Pregnancy outcomes in patients with multiple sclerosis treated with teriflunomide: Clinical study data and 5 years of post-marketing experience. Mult Scler 2020; 26: 829–836.

45.

Andersen

Wandall-Holm

Magyari

Pregnancy outcomes following maternal or paternal exposure to teriflunomide in the Danish MS population. Mult Scler Relat Disord 2022; 59: 103529.

46.

Pauliat

Onken

Weber-Schoendorfer

, et al. Pregnancy outcome following first-trimester exposure to fingolimod: A collaborative ENTIS study. Mult Scler 2021; 27: 475–478.

47.

Platzbecker

Wentzell

Kollhorst

, et al. Fingolimod, teriflunomide and cladribine for the treatment of multiple sclerosis in women of childbearing age: Description of drug utilization and exposed pregnancies in Germany. Mult Scler Rel Dis 2022; 67: 104184.

48.

Dubinsky

Charles

Selmaj

, et al. Pregnancy outcomes in the ozanimod clinical development program in patients with ulcerative colitis, Crohn’s disease, and relapsing multiple sclerosis. Inflam Bowel Dis 2024; 30: 2512–2515.

49.

Novartis. Gilenya 0.25 mg hard capsules, https://www.medicines.org.uk/emc/product/4545/smpc (2025, accessed 31 August 2025).

50.

Novartis. Mayzent 0.25 mg film-coated tablets, https://www.medicines.org.uk/emc/product/11019/smpc (2025, accessed 31 August 2025).

51.

Bristol Myers Squibb Pharmaceuticals. Zeposia 0.23 mg hard capsules, https://www.medicines.org.uk/emc/product/11906/smpc (2025, accessed 31 August 2025).

52.

Laboratoires Juvise Pharmaceuticals. Ponvory 2, 3, 4, 5, 6, 7, 8, 9, 10 mg film-coated tablets, https://www.medicines.org.uk/emc/product/100488/smpc (2025, accessed 31 August 2025).

53.

Jeantin

Bensa-Koscher

Deschamps

, et al. Multiple sclerosis reactivations after fingolimod discontinuation for pregnancy planning. J Neurol Neurosurg Psychiat 2024; 96: 334629.

54.

Hellwig

Tokic

Thiel

, et al. Multiple sclerosis disease activity and disability following cessation of fingolimod for pregnancy. Neurol Neuroimmunol Neuroinflamm 2023; 10: 1–12.

55.

Datta

Hale

Thiel

, et al. Low transfer of cladribine into human milk. Mult Scler J 2023; 29: 1346–1347.

56.

LEMTRADA 12 mg concentrate for solution for infusion, https://www.medicines.org.uk/emc/product/15496/smpc (accessed 19 October 2025).

57.

Ziemssen

Bass

Berkovich

, et al. Efficacy and safety of alemtuzumab through 9 years of follow-up in patients with highly active disease: Post hoc analysis of CARE-MS I and II patients in the TOPAZ extension study. CNS Drugs 2020; 34: 973–988.

58.

van Dorp

Haupt

Anderson

, et al. Reproductive function and outcomes in female survivors of childhood, adolescent, and young adult cancer: A review. Journal of Clinical Oncology 2018; 36: 2169–2180.

59.

Salooja

Michonneau

Tichelli

, et al. Conception and pregnancy outcomes after haematopoietic stem cell transplant: A retrospective study from the transplant complications working party of the European Society for Blood and Marrow Transplantation. Blood 2018; 132: 2139–2139.

60.

Sockel

Neu

Goeckenjan

, et al. Hope for motherhood: Pregnancy after allogeneic hematopoietic cell transplantation (a national multicenter study). Blood 2024; 144: 1532–1542.

61.

Maillart

Rollot

Leray

, et al. Pregnancy and birth outcomes in women with multiple sclerosis: Comparison of the RESPONSE study to the general French population. Mult Scler 2025; 31: 324–337.