Multiple Sclerosis During Pregnancy and Breastfeeding

Multiple sclerosis (MS) is a neurological disorder that afflicts the brain, the spinal cord, and the optic nerves. It is a chronic disease, meaning that it starts up gradually and worsens throughout life, sometimes with some waxing and waning, coming with flare ups, separated by periods of remission. Alternatively, MS can begin more quickly. Either way, it leads to worsening disabilities in sensation, movement, and balance, along with problems in urination. MS can complicate pregnancy, as the disease often begins in the prime of life. Very often, MS can improve during pregnancy, but following delivery can come back in full force. MS is thought to be an autoimmune condition, meaning that your own immune system is the underlying cause. In the case of MS, scientists think that the immune system attacks sheaths of myelin, a fat-like material that surrounds the long appendages of neurons (nerve cells), known as axons. In healthy neurons, myelin enables axons to transmit electrical signals quickly. Thus, destruction of myelin sheaths interferes with electrical transmission in nervous tracts (bundles of axons that carry signals through the brain and spinal cord).

Unlike many conditions that strike older people, MS typically shows itself during a woman’s younger to middle age years (ages 20-45 years). MS also is twice as common in women than in men. Putting these two factors together makes MS fairly common in pregnant women, but there are other factors that can increase the risk that you will develop MS, namely:

  • Having a sibling or parent with MS, and especially having an identical twin with MS.
  • Being of European (Caucasian) descent
  • Living at higher latitude locations (farther from the Equator), especially during the first few years of life
  • Higher socioeconomic status

Furthermore, the following factors are suspected of increasing the MS risk:

  • Deficiency of vitamin D
  • Use of tobacco use, or secondhand tobacco smoke exposure
  • History of infection with Epstein-Barr virus (EBV), the virus that most commonly causes of mononucleosis (“mono”)

If your doctor suspects that you may be developing MS, the first step is a thorough review and expansion of your medical history that highlights problems in movement, balance, and vision and brings out information concerning family members who may have MS, or who may have been afflicted with the condition. You will be given a physical examination that will include evaluation of your vision and eye movement muscles, tests of your reflexes (including how your pupils react to light), and testing of mental functions, such as your memory ability to concentrate. If the doctor has any suspicion at all after the exam that you may have MS, the doctor will refer you to a neurologist, who will perform a more complex physical examination, and also review your history. The neurologist also will order laboratory testing and imaging studies. The laboratory studies will be performed on samples of your blood and will be selected to screen for signs that the immune system has turned against the nervous system. Diagnosis of MS will depend on imaging, especially magnetic resonance imaging (MRI), which can detect about 90 percent of MS cases. Additionally, the neurologist may order electrical testing of your muscles, and will order lumbar puncture in which a needed is inserted into the canal that holds fluid around the lower spinal cord, in order to draw fluid that can be studied with more laboratory tests.

Often, during pregnancy, MS symptoms improve, but if the disease has already progressed to movement, balance, and bladder problems, the growing womb can exacerbate them. Although MS does not affect the fetus directly, doctors often need to adjust the therapy before pregnancy begins, since not all of the medications that are given for MS are safe during pregnancy. MS medications include a group of drugs called immunomodulating agents. These agents include natalizumab, rituximab, alemtuzumab, acrelizumab, glatiramer acetate, and interferon beta, and they are given to prevent new attacks from occurring. Nevertheless, during pregnancy, you must stop taking these agents; furthermore, some MS-fighting agents need to be “washed out” of the body before pregnancy begins. An exception is natalizumab, which women with severe MS may continue to take.

Washing out is accomplished by stopping use the medication for a particular amount of time before beginning pregnancy. The amount of time that you will need for washout varies based on the medication. Fingolimod requires a 2-month washout period, for instance, before pregnancy, whereas Dimethyl fumarate and natalizumab each require a one month pre-pregnancy period. If you are taking alemtuzumab, you need a 4-month pre-pregnancy washout, but if you take mitoxantrone, a 6-month washout period is enough. In the case of teriflunomide, a special special elimination procedure is needed to lower the level of the drug in your blood to 0.02 µg/ml, or less, before you become pregnant. Usually, MS calms during pregnancy, but in the even that you suffer an MS flare up after becoming pregnant, your neurologist can treat you with a corticosteroid called methylprednisolone.

Despite all that we have discussed above, most of the time women with MS can have normal pregnancies. MS is a condition that makes people extremely fatigue, which in combination with pregnancy can be all the more difficult. However, since MS symptoms often lessen while you are pregnant, having MS does not necessarily mean that your pregnancy will be considered complicated. Many women with MS do require cesarian section (surgical delivery) for a variety of reasons, but usually not because if the MS itself, and usually there is no reason why you can’t deliver vaginally.

When it comes to breastfeeding, there is concern and uncertainty about the safety of various MS drugs. Since many women relapse following delivery, therapy with powerful MS drugs such as immunomodulators often needs to start up again. Until more is known about how easily these agents enter breask milk, depending on the severity of your flare up and the drug that you are given, you may or may not be able to breastfeed. In some cases, you may be able to pump and store breast milk for a period of time after after you deliver, and then start up treatments for MS medications and stop pumping and nursing. Then, you can feed the baby your stored milk from a bottle and transition to infant formula.

David Warmflash
Dr. David Warmflash is a science communicator and physician with a research background in astrobiology and space medicine. He has completed research fellowships at NASA Johnson Space Center, the University of Pennsylvania, and Brandeis University. Since 2002, he has been collaborating with The Planetary Society on experiments helping us to understand the effects of deep space radiation on life forms, and since 2011 has worked nearly full time in medical writing and science journalism. His focus area includes the emergence of new biotechnologies and their impact on biomedicine, public health, and society.

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