Pregnancy and Myasthenia Gravis

Reviewed by: HU Medical Review Board | Last reviewed: May 2021

Women who develop myasthenia gravis (MG) often do so during their 20s and 30s. This also happens to overlap when many women plan to start having babies.1-3

Myasthenia gravis is an autoimmune condition well-known for its unpredictable and changing symptoms. This variability continues during pregnancy for women with MG. Some have few problems other than typical pregnancy issues, and others have MG flares.1-3

In general, women whose MG is stable can expect to have a normal pregnancy and delivery. For women with active MG, the first trimester and postpartum period are when symptoms most often get worse. About 1 out of 3 women flare during the postpartum period, or up to 6 weeks after delivery.1,2

Planning ahead

If at all possible, a woman should work with her neurologist and gynecologist well ahead of the time she wants to get pregnant. This gives the doctor time to change any MG treatments that may be unsafe for an unborn baby. It may also take some time to find the right combination of new treatments that control the muscle weakness of MG yet are safe for pregnancy.

In addition, extra tests may be needed before getting pregnant. These tests are used to measure pre-pregnancy:1

  • Muscle strength
  • Breathing strength and lung function
  • Heart health
  • Thyroid function

A woman with MG needs to be followed closely by her neurologist and a maternal-fetal medicine (MFM) specialist throughout her pregnancy. An MFM is an obstetrician who specializes in caring for women with high-risk or complicated pregnancies. It may be necessary to plan to deliver at a facility with a neonatal intensive care unit (NICU) just in case there are complications like neonatal MG.2

Delivery by cesarean section (C-section) should be avoided if possible because people with MG often react poorly to anesthesia. However, if the need for a C-section is known ahead of time, a woman with MG can be treated with intravenous immunoglobulin (IVIG) or plasmapheresis to decrease the risk of an MG flare later. An epidural may be recommended for vaginal delivery and is considered safe in most women with MG.2,3

Pregnant women are at the highest risk of dying due to their MG symptoms if they get pregnant in the first 2 years after symptoms began. This risk decreases the longer a woman has had MG. This is why doctors recommend that women avoid getting pregnant for 2 years or longer after diagnosis.1,4

Having a thymectomy in the years before getting pregnant also seems to provide some protection to both the mother’s and baby’s health.1

Treatments during pregnancy

The good news is that many standard MG treatments are safe to take during pregnancy. Anticholinesterase inhibitors are the mainstay of treatment, and they are generally safe to take while pregnant.3

If MG symptoms are not well controlled with anticholinesterase inhibitors alone, immunosuppressants may be needed. Steroids and other immunosuppressants, including azathioprine, cyclosporine, and rituximab, have been used safely in pregnant women with MG.3

Managing myasthenia gravis

To limit or prevent MG flares or a myasthenic crisis, pregnant women with MG must:1

  • Have any infection treated quickly
  • Avoid physical and emotional stress as much as possible
  • See their doctor immediately if a cough, shortness of breath, or other signs of an MG flare develop

Mycophenolate mofetil, methotrexate, and cyclophosphamide cause birth defects and should not be taken before or during pregnancy, or while breastfeeding.3

If a woman does have a serious MG flare or myasthenic crisis, plasmapheresis and IVIG can be used safely. Plasmapheresis and IVIG may also be recommended before giving birth, especially if a C-section is planned. These therapies can prevent a postpartum or post-anesthesia MG flare.1,3

Neonatal MG

Up to 2 out of 10 babies born to mothers with MG will have temporary muscle weakness. This is called transient neonatal myasthenia gravis. Neonatal MG usually begins a few hours after birth and wears off after a few weeks.1

Many babies with this condition require little to no treatment. Those with more severe weakness may temporarily need acetylcholinesterase inhibitors and changes to their feeding schedule to help them feed better.1

These babies do not have a greater risk of developing MG later in life. However, if a woman has 1 baby with neonatal MG, she has a 3 out of 4 chance that her next babies will also have the condition.1

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