Multiple sclerosis does not appear to lower the chance of conceiving, and relapses tend to decrease during pregnancy — especially in the third trimester — before rising for a time after birth. The real planning work is your disease-modifying therapy (DMT): some can be continued until conception, some need a washout, and some carry rebound risk if stopped. That timing is a decision for your neurologist, ideally made months before you stop contraception.
Your DMT sets the timeline
MS and fertility: what the evidence shows
A 2023 review from the Cleveland Clinic’s Mellen Center for Multiple Sclerosis, built around 20 common family-planning questions, reports that conception and fertility rates in people with MS are comparable to the general population. In other words, MS itself is not usually the reason a pregnancy takes time.
What MS can affect is sex and intimacy. The same review notes sexual dysfunction is very common — reported in 40% to 80% of women and 50% to 90% of men with MS — through fatigue, sensory changes, bladder symptoms, mood, medications, or erectile difficulties. These are treatable, and they are worth raising directly with your neurologist or a urologist or gynecologist. If timed sex is starting to feel like a chore stacked on top of MS fatigue, that is a common experience, not a personal failing.
If you have been trying for a while without success, the same timelines everyone else uses apply. See when to see a fertility specialist.
What pregnancy does to relapse risk
The classic data come from the PRIMS study, published in the New England Journal of Medicine in 1998, which followed 254 women through 269 pregnancies. In the group followed through first pregnancies, relapse rates looked like this:
| Period | Relapses per woman per year (PRIMS) |
|---|---|
| Year before pregnancy | 0.7 |
| First trimester | 0.5 |
| Second trimester | 0.6 |
| Third trimester | 0.2 |
| First 3 months after birth | 1.2 |
Those numbers come from an era before most of today’s therapies. The Mellen Center review summarizes more recent data: relapse rates still decline progressively through the trimesters, and about 13% of women have a clinical relapse within three months of delivery. It also notes a pattern that matters for planning: people with more relapses before conception are more likely to stay active during pregnancy, and annualized relapse rates stay higher through pregnancy after stopping fingolimod or natalizumab than after lower-efficacy therapies.
The practical takeaway is that disease activity going into pregnancy, and how your DMT is stopped, shape what happens during and after. That is why the DMT plan is the center of MS family planning.
DMT planning is a prescriber decision — here is what to ask about
There is no single washout rule for “MS drugs.” Each therapy behaves differently. The overview below reflects the Mellen Center review; it is meant to help you ask good questions, not to choose for you.
| Therapy type | What the review describes |
|---|---|
| Interferons, glatiramer acetate | Generally stopped before planned conception, but may be continued in lower-risk situations when benefits outweigh risks. |
| Teriflunomide | Contraindicated in pregnancy; requires an accelerated elimination procedure before conception. Applies to men too (see below). |
| Cladribine | Embryo harm in animal studies; pregnancy avoided for a period after treatment. |
| Fingolimod and other S1P modulators | Stopping carries a rebound risk. Switching to a B-cell-depleting therapy before stopping contraception may be considered, especially with highly active disease. |
| Natalizumab | Also carries rebound risk when stopped; use during pregnancy is reserved for exceptional situations. |
| Anti-CD20 therapies (ocrelizumab, ofatumumab, rituximab, ublituximab) | Labels recommend contraception for months after the last dose; the review describes approaches where conception is timed in the months after a dose to limit later-pregnancy exposure. |
| Alemtuzumab | Not advised during pregnancy. |
- How is my current DMT handled before and during pregnancy?
- Is there a washout or elimination procedure, and how long does it take?
- Is there a rebound risk if I stop, and should I switch first?
- How long can I safely try to conceive off treatment before we reassess?
- Do I need an MRI before we start trying?
- What is the plan for restarting after birth, and does it depend on breastfeeding?
If the partner with MS is not the one getting pregnant
Family planning with MS is not only about the person carrying the pregnancy. The Mellen Center review highlights a few therapies where the sperm-providing partner needs a plan too:
- Teriflunomide: men are advised to use contraception until the drug is cleared — at least six months after the last dose, or after an accelerated elimination procedure — and partners should be counseled.
- Cladribine: men are advised to avoid conceiving for at least six months after treatment, and the drug can cause reversible infertility through non-moving sperm.
- Alemtuzumab: can cause reversible male infertility.
If this applies to your household, make sure the partner with MS raises pregnancy plans with their own neurologist. General sperm-health basics are covered in how to improve sperm health.
Fertility treatment and MS
Some people with MS need IUI or IVF for the same reasons anyone does. The review notes that some older studies linked assisted reproduction to relapses in the three months after unsuccessful cycles, while a more recent study did not find this. If you are heading toward fertility treatment, loop your neurologist and fertility clinic together, so DMT timing and stimulation cycles are planned as one schedule rather than two.
MRI and imaging around pregnancy
MRI is generally avoided during pregnancy unless the result would critically change decisions, and gadolinium contrast is used cautiously. That makes the preconception window a reasonable time to ask whether an updated scan would help set your baseline. During breastfeeding, the review notes gadolinium may be used when necessary.
The postpartum plan and breastfeeding
Because relapse risk rises after birth, the postpartum plan deserves as much attention as the conception plan. The review notes that most DMTs are considered unsafe during breastfeeding, with some exceptions and nuances — glatiramer acetate has EU approval for use while breastfeeding, interferons pass into milk in low amounts, and B-cell therapies yield low infant doses. It also notes that IV methylprednisolone for a relapse can be given while breastfeeding.
That means feeding plans and DMT restart timing are linked. Some people prioritize restarting treatment quickly; others prioritize breastfeeding with a compatible option. Neither is wrong. Deciding before birth means you are not making it at 3 a.m. with a newborn. If you are already thinking ahead to a second pregnancy, our guide to getting pregnant while breastfeeding covers the fertility side.
- Line up sleep support. Fatigue and broken sleep hit harder with MS.
- Plan who handles night feeds or bottle prep if you restart a DMT that is not compatible with breastfeeding.
- Know who to call if new symptoms appear in the first months after birth.
Will my child get MS?
It is one of the most common worries. The review reports that children of a parent with MS have about 5.77 times the general population’s risk — but the absolute risk is still roughly 2%. Put another way, most children of parents with MS do not develop it. Many genes and environmental factors are involved, including smoking, vitamin D levels, and adolescent obesity.
The National MS Society maintains a family planning and pregnancy section that is a good next stop for community stories and support resources.
Frequently asked questions
Does MS make it harder to get pregnant?
Generally no. A 2023 Cleveland Clinic Mellen Center review reports that conception and fertility rates in people with MS are comparable to the general population, although sexual dysfunction is common and worth treating.
Do MS relapses get better during pregnancy?
Usually. Relapse rates tend to decline across the trimesters, most in the third, then rise for a time after birth. In the 1998 PRIMS study, relapse rates dropped to 0.2 per year in the third trimester and rose to 1.2 per year in the first three months after delivery.
How long before trying to conceive should I stop my DMT?
It depends entirely on the drug. Some can be continued until conception in selected cases, some need an elimination procedure, and some carry rebound risk if stopped. Your neurologist should set the timing.
Can men with MS father a child while on treatment?
Often, but a few therapies need planning. Teriflunomide requires contraception until the drug is cleared, cladribine requires waiting at least six months, and alemtuzumab can cause reversible male infertility. Discuss plans with the neurologist.
What is the chance my child will develop MS?
The Mellen Center review reports an absolute risk of roughly 2% for children of a parent with MS, which is higher than the general population but means most children will not develop it.
Sources & guidance
- Cleveland Clinic Journal of Medicine (2023): Mellen Center consensus answers on MS during family planning, pregnancy, and postpartum
- Relias Media: Effect of Pregnancy on Multiple Sclerosis (summary of Confavreux et al., NEJM 1998;339:285-291, PRIMS)
- National MS Society: Family Planning & Pregnancy with MS
- MS International Federation: Pregnancy and parenting