Patients diagnosed with myasthenia gravis (MG), a chronic condition characterized by muscle weakness and fatigue, may start noticing symptoms when they are in their 20s and 30s — also the age when many women are thinking about having children. While an MG diagnosis during childbearing years can be concerning, it may be reassuring to know that generally, if the neuromuscular disease is well controlled, pregnancy is considered to be safe for patients.
Still, having MG and being pregnant can increase the chance of complications. For this reason, medical monitoring and specific treatments may be recommended to ensure a safe pregnancy and birthing experience.
As such, pregnant women with MG may wish to set up a healthcare team that includes an obstetrician and a neurologist who are both familiar with the rare disorder.
Myasthenia gravis usually is caused by self-reactive antibodies that attack proteins involved in nerve-muscle communication, affecting muscles involved in the body’s voluntary movements. Most commonly, these autoantibodies attack proteins known as acetylcholine receptors.
In some cases, the babies of mothers with the disease may be born with a temporary condition called transient neonatal MG. This occurs when a mother with MG passes on her self-reactive antibodies to her unborn baby in the womb, causing a similar autoimmune response in the fetus. Symptoms usually disappear within a few weeks or months with supportive treatment.
To best ensure the health of both the mother and her unborn child, it’s recommended that a woman with MG works with her healthcare team to devise a treatment plan for use during pregnancy.
Myasthenia gravis and pregnancy planning
When a woman with MG is planning to become pregnant or is pregnant, it’s recommended she speak with her healthcare provider about her treatment. Key to such discussions is whether any medications she is taking for MG need to be changed or adjusted.
Fatigue is a common side effect of pregnancy, which may be worse for pregnant women with MG. A woman with MG who is pregnant should monitor her energy levels. She may need to plan frequent short breaks, and naps, into her daily routine to reduce pregnancy-related fatigue and MG-related muscle weakness.
Some women may notice that their symptoms are worse, while others may have no change, or see their symptoms ease. If pregnancy worsens MG symptoms, it is often most noticeable during the first trimester of pregnancy and/or in the first six months postpartum, or the time period after giving birth.
While there always is a risk for complications during pregnancy, women with myasthenia gravis have a slightly higher risk. One potential complication is having a myasthenic crisis while pregnant. Any myasthenic crisis, typically defined as experiencing severe breathing problems that require hospitalization, will need to be treated carefully during pregnancy.
It’s important for women with MG to attend regular prenatal visits and contact their healthcare provider if they notice anything unusual with their pregnancy or any changes in their MG symptoms.
Per this guidance, if pregnant women with MG have their disease under good control before pregnancy, the majority of patients will remain stable throughout the pregnancy period.
This global guidance suggests oral pyridostigmine (sold as Mestinon and generic versions) as a first-line treatment during pregnancy. Importantly, intravenous or into-the-vein formulations of acetylcholinesterase inhibitors, including pyridostigmine, should not be used during pregnancy as they may result in uterine contractions.
Regarding immunosuppressors, prednisone is the agent of choice during pregnancy, according to healthcare providers.
Any plans for a thymectomy — a surgical procedure recommended to some MG patients to remove the thymus gland, which is part of the immune system — should be postponed until after pregnancy.
In the months leading up to labor, it’s important for women with MG to speak with their healthcare providers about their options for delivery.
Most women with MG have vaginal births. But a Cesarean section, or surgery to deliver the baby through the mother’s abdomen, may be recommended if becoming too exhausted during labor is a concern.
Transient neonatal MG
If you have MG, then your newborn should be monitored for symptoms of transient neonatal MG. It is due to the mother’s self-reactive antibodies being passed on to the fetus during pregnancy. This can potentially trigger a comparable autoimmune response in the newly born child.
It is believed that around 10% to 20% of babies born to mothers with MG will develop transient neonatal MG.
Signs of transient neonatal MG typically become noticeable in a newborn shortly after birth and may include:
impaired suckling or swallowing
respiratory insufficiency or a weak cry.
Newborns should be monitored for the first few days or weeks following birth for signs of transient neonatal MG.
Infants with transient neonatal MG are not at a higher risk of developing MG or juvenile myasthenia gravis as children or later in life.
Typically, babies with transient neonatal MG recover with supportive treatment as maternal autoantibodies gradually clear from their system.
It’s also important that new mothers with myasthenia gravis receive appropriate care during the postpartum period.
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