woman cradling her pregnant stomach

How MS Affects Pregnancy and Fertility

By Kerry Weiss
Reviewed by Dana Cooper, M.D.
April 10, 2023

Multiple sclerosis (MS) is at least two to three times more common in women than it is in men, and it’s commonly diagnosed between ages 20 and 50. This means that many people are dealing with an MS diagnosis during their childbearing years and may wonder how this unpredictable neurological condition can affect their family planning. Here are some answers to commonly asked questions about how MS affects fertility, pregnancy, and reproductive health.

Does MS make it difficult to get pregnant?

Most people with MS don’t have any more difficulty than non-MS patients with becoming pregnant. It’s been estimated that about 10% of people with MS do experience fertility challenges, but that’s similar to the rate of the general population. And fertility treatments, especially in vitro fertilization (IVF), can be a helpful option for some people who are having trouble conceiving. IVF is estimated to be successful in up to 39% of women under age 35 who have MS, according to research.

Some research suggests that women who have MS and use fertility treatment may experience an increased risk of relapse, especially in the three months after an unsuccessful IVF attempt. This is thought to be related to the use of gonadotropin-releasing hormone (GnRH) agonists in fertility treatment, which can promote inflammation in the body. But researchers aren’t certain of that, theorizing that the increased relapse rate could instead be due to temporarily discontinuing disease-modifying treatment or increased stress related to fertility treatments.

A more recent 2019 study didn’t show clear-cut results and exposed a need for more studies to be done on assisted reproduction and MS relapse rates. Researchers are continuing to investigate this area with the hope of providing concrete recommendations for people with MS seeking fertility treatment.

How does pregnancy affect MS?

“For most women, pregnancy is actually pretty compatible with MS,” says Thomas Frederick McElrath, M.D., Ph.D., associate professor of obstetrics and gynecology at Harvard Medical School and attending physician in maternal-fetal medicine at Brigham and Women’s Hospital, in Boston. For the most part, MS-related issues during pregnancy tend to be more of the exception than the rule.

One of the most notable changes that comes with pregnancy is that MS tends to go into remission during pregnancy—particularly as the pregnancy progresses. “In the first trimester, there's really not much of an effect of pregnancy on MS,” explains James W. Stark, M.D., a board-certified neurologist at the International Multiple Sclerosis Management Practice, in New York City. “But in the second and third trimester, it's extremely rare to have an MS attack.”

However, some people find pregnancy to be physically taxing, which can worsen MS symptoms like fatigue. Pregnancy can also exacerbate MS-related bladder issues, and those who rely on a wheelchair may experience more urinary tract infections (UTIs) during these nine months. Symptoms like muscle weakness or balance or coordination problems may become worse as the baby—and belly—gets bigger, which can also increase the risk of falls during pregnancy.

Are MS treatments safe to take during pregnancy?

The FDA uses a drug classification system to categorize medications based on safety profile. Most MS drugs are labeled as Class C, which means studies of these drugs in pregnant lab animals found them to have adverse effects on the animals’ fetuses. But most of these medications have not undergone extensive studies in pregnant humans to evaluate their safety. Therefore, most MS treatments are not considered to be safe to use during pregnancy.

“There are certain drugs that are absolutely contraindicated when trying to get pregnant,” Stark says. That’s why, for some people with MS, that may mean using birth control while taking their MS treatments and working with their healthcare team to decide when to stop taking that medication in order to start trying to conceive.

Nevertheless, Stark says, “There are a few drugs that are considered to be safe during pregnancy.” Some medications come with some risks, which may or may not outweigh the risks of a potential relapse. Decisions around MS treatment during pregnancy are dependent on factors like the type of medication, how well your MS is currently controlled, and the risk of relapse.

If you’re considering becoming pregnant, McElrath advises bringing questions to a maternal-fetal medicine specialist, a doctor who helps treat pregnant people with chronic health conditions, high-risk pregnancies, and/or complications.

“I would suggest that if a [person with MS] is on a stable regimen that's working for her, she should have a pre-pregnancy consultation with a high-risk obstetrician and decide what's the best way to go,” McElrath says, “because a lot of times, it's better to stay on something that's working than it is just to go off and potentially provoke a flare just as someone's getting pregnant or is in the first trimester, which could actually be more of a risk.”

How can I safely address a flare during pregnancy?

Those who experience an MS attack during pregnancy should tell their doctor as soon as possible. Short-term corticosteroid treatment is often considered safe for helping control a flare, particularly during the second or third trimester.

“Corticosteroids don't tend to cross the placenta, so when used for more limited periods of time, the baby is basically shielded from them,” McElrath says.

If you have concerns about your MS and are considering getting an MRI, it may be reassuring to know that an MRI is considered safe during pregnancy if it’s without gadolinium contrast (an IV medication). “An MRI is a magnet, not radiation, so it's perfectly safe,” Stark says. This means that an MRI can be used to monitor MS during any trimester.

Does MS pose health risks to the baby?

Generally speaking, there’s no proof that MS increases the risk of miscarriage, stillbirth, or birth defects.

However, there is some evidence that people with MS are more likely to give birth to babies that are slightly smaller than other babies of the same gestational age.

Because genes are thought to play a role in the development of MS, some people worry that they’ll pass MS on to their child. But experts say MS isn’t caused by a single gene, and so it’s not likely this will happen. “MS is not a genetic disease the way that other diseases are,” explains Stark. “Depending on the study you look at, there's about a 2% to 4% risk of a first-degree relative of someone with MS also having MS.”

How does having MS affect labor and delivery?

Researchers have identified that there may be a slightly increased risk of preterm delivery in people with MS.

Some people with MS may have trouble giving birth vaginally, especially if MS symptoms affect the pelvic muscles and nerves involved in pushing. This may result in an assisted vaginal delivery, which may include the use of forceps or a vacuum, or it may mean they need to deliver via cesarean section.

Some people who have MS may have reduced abdominal sensation and therefore may not feel pain with contractions and can have a hard time knowing when they’re in active labor. Separately, for those interested in pain management options during labor and delivery, the use of an epidural is considered safe in MS.

What can a person with MS expect during the postpartum period?

While MS tends to go into remission during pregnancy, there’s a well-known increased risk of relapse within the first three months postpartum.

That said, recent research—a 2019 review and a 2020 study—found that breastfeeding may actually reduce the risk of these postpartum MS attacks. That’s not to say breast/chestfeeding can prevent postpartum relapses altogether, but the results were encouraging.

The catch is that many MS medications are not recommended for use while nursing. “Certainly breastfeeding for a few weeks is a very good idea,” Stark says, “but then you have to balance the risk of continued breastfeeding versus going back on your MS drug.”

Stark goes on to explain that many doctors will order an MRI around six weeks postpartum, and if anything comes up on the MRI that shows active disease, then aggressive treatment is usually recommended. At that point, you’ll likely want to talk to your doctor about whether you should continue breast/chestfeeding.

If you do wish to keep nursing, it’s important to work with your healthcare team to determine which treatment options can help keep your MS under control without posing a risk to your baby.

Something else to be aware of is postpartum depression. Approximately 1 in 7 of all birthing parents experience postpartum depression—and factors like fatigue, disability, or impaired movements related to MS can contribute to depression. Talk with your healthcare team if you experience feelings of sadness, indifference, and anxiety, or changes in appetite, energy levels, and sleep habits that persist beyond the first few weeks after bringing your newborn home.

When is the right time to talk about having a baby?

MS is a highly individualized condition, so it’s important to talk with your healthcare team before you start trying to conceive.

“Ideally, a pre-pregnancy consultation with both [your obstetrician and neurologist] would be the best way to go, just to make sure everything’s in order,” advises McElrath.

From there, you can work together to decide the next steps for your health and that of your growing family.

Try to stay calm and positive—because the odds are in your favor. “By and large,” McElrath says, “most people with MS do pretty well when they're pregnant.”

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