MS Onset May Be Delayed 3 Years by Pregnancy and Childbirth: Study

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Key Takeaways

  • Pregnancy appears to reduce the onset of the first symptoms of multiple sclerosis for three years.
  • The protective effect appears strongest in pregnancies that go through the second and third trimesters, when hormones calm an overactive immune system.
  • Pregnancy hormones may change the expression of genes connected with the immune system, protecting not only the fetus but also reducing relapses of MS.
  • Onset of MS was not further delayed in women with multiple pregnancies.

Pregnancy may delay the onset of the first symptoms of multiple sclerosis (MS) for more than three years, according to new research from Monash University in Australia.

MS affects three times more women than men, and the disease often is diagnosed during a woman’s childbearing years. Women with MS may struggle with the decision to start a family because they are unsure how their disease would affect their pregnancy. Now, a study of more than 2,500 women shows that pregnancy likely has a positive effect on MS. 

The findings, published in JAMA on September 14, show the positive effect occurs with just one pregnancy and delivery. However, having multiple pregnancies and giving birth multiple times did not further delay the onset of symptoms. 

 “What this study shows us is that pregnancy can delay the onset of clinically isolated syndrome (CIS)—a precursor to a diagnosis of MS—by many years,” Vilija Jokubaitis, PhD, senior research fellow in the department of neuroscience at Monash University and senior author of the study, tells Verywell.

The study looked at the reproductive histories of 2,557 women from the age of 16 to the point in time they experienced CIS. The researchers were able to analyze more than 10 years of follow-up data available in most cases. The results show the median delay in CIS diagnosis; 3.3 years if pregnant, 3.4 years with a live birth. Jokubaitis says there is no estimation of the maximum amount of time that CIS could be delayed.

“Everyone in our study did eventually develop CIS; pregnancy and childbirth cannot delay the onset of disease indefinitely,” Jokubaitis says. “Still, three extra years of living free of a first demyelinating event is a very long time.”

What MS Does To Your Body

MS is a chronic disease that affects the central nervous system—that is, the brain and the spinal cord. Nerves to the rest of the body branch out from the central nervous system to send and receive messages. If you burn your finger or cut your foot, nerves relay that news to your brain, and your brain quickly sends the signal to pull your hand away from the heat or lift your foot to see what you stepped on. But nerves also keep your heart beating and your lungs pumping. They send pain messages when you have a problem with an organ, such as a kidney stone, or a bladder infection.

Normal, healthy nerves are surrounded by a protein called myelin, which forms a protective sheath, much like the insulation around electrical wires. When the insulation around wires wears away, the exposed wires may potentially cause a short. MS is similar in that the myelin sheath wears away a process called demyelination—and the underlying nerve may potentially have trouble sending and receiving signals. The result is symptoms such as numbness, tingling, shock-like sensations, and trouble with vision, movement, or balance, to name a few.

 “MS is an autoimmune condition where the immune system is overactive,” Jokubaitis says. The immune system cells attack the myelin protein, damaging nerves.

CIS—a first episode of neurologic symptoms that lasts at least 24 hours and is caused by demyelination, according to the National MS Society—may be the start of MS, or it could be a one-time occurrence. People who experience CIS won’t know if they have MS until another neurologic episode occurs at least one month later and damages a second spot in the central nervous system. And, of course, all other potential causes must be ruled out. 

Pregnancy’s Effect On the Immune System

Pregnancy is well known for the way it changes a woman’s body on the outside: larger breasts, expanding belly, glowing skin. But many changes happen on the inside, too, not the least of which occur in the immune system. 

 “Pregnancy is a unique circumstance in which a woman’s body is harboring another organism—the fetus—that would normally be identified as a foreign invader and be attacked and rejected by the immune system, like a mismatched organ transplant,” Kathleen Costello, MS, CRNP, MSCN, associate vice president of healthcare access at the National MS Society tells Verywell.

The immune system goes through a number of stages to ensure a successful pregnancy, explains Jokubaitis. “Initially, the immune system needs to be more inflammatory to ensure successful embryo implantation,” she says.

Once the fetus is growing and developing, the immune system dampens down to protect the fetus. “The changes that the immune system undergoes to ensure a successful pregnancy means that, overall, it is less inflammatory,” Jokubaitis says. “This dampening down to protect the fetus also helps to alleviate MS symptoms.”

But as the body prepares to give birth, the immune system once agains becomes inflammatory, Jokubaitis says. “It could be that these periods of increased inflammatory activity to ensure pregnancy success might exacerbate an already overactive immune system, and lead to a first MS diagnosis in some women,” she says. “In our study [of more than 2,500 women], we actually identified 71 women, or 3% of our participants, who were diagnosed with a CIS during their pregnancy.”

Next Steps

Research will continue for women with MS. “In my laboratory, we are now seeking to understand the exact biological mechanisms that underpin improved outcomes in women with MS while they are pregnant,” Jokubaitis says. “Unfortunately, it’s not as straightforward as a single hormone being responsible for this [effect], as previous clinical trials have shown.”

The studies on pregnant women with MS could benefit all people with MS, with new therapies possible in the future. “It won’t be as straightforward as hormone therapy or even combination hormone therapy,” Jokubaitis says. “However, we hope that by understanding the biology of pregnancy a bit better, both in MS and in health—it’s incredible how much we don’t know—then we might be able to identify new and more specific therapeutic targets and strategies.”

What This Means For You

If you have MS and are pregnant, this study offers hope of a respite from symptoms while pregnancy hormones keep the immune system from being overactive. Although the respite is welcome, it is not permanent, so you’ll want to do whatever you can to stall the return or increase of symptoms after giving birth. To do that, you can start before you get pregnant, by talking to your doctor about getting your MS under good control.

“There is some evidence that disease stability prior to pregnancy generally equates to fewer relapses or new disease activity postpartum,” Costello says. 

How can you stabilize your MS? Costello recommends the following to help reduce symptoms and/or new disease activity, all of which you should discuss with your neurologist:

  • Take a disease-modifying therapy regularly prior to becoming pregnant
  • Practice a healthy lifestyle 
  • Get back onto an MS disease-modifying therapy as soon as possible after giving birth
  • Consider exclusively breastfeeding without supplementing with formula
3 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Nguyen A, Vodehnalova K, Kalincik T, et al. Association of pregnancy with the onset of clinically isolated syndrome. JAMA Neurol. doi:10.1001/jamaneurol.2020.3324

  2. National Multiple Sclerosis Society. Pregnancy and Reproductive Issues.

  3. National Multiple Sclerosis Society. Clinically Isolated Syndrome (CIS).

By Donna Siegfried
Donna Siegfried is an award-winning journalist with over 30 years' experience. She is a member of the American Medical Writer’s Association.