Women with myasthenia gravis are just as likely to have healthy babies as women without the condition, and they are no more likely to have miscarriages or stillbirths. Because of their disease, however, they may feel weaker and more tired than usual during pregnancy. In addition, their babies might be slightly smaller than babies born to women without the condition, but the lower birth weight does not affect the babies' health or development. It's not clear whether the lower weight is a result of the disease or the medications.
Before conceiving, patients should talk to their neurologists and obstetricians about their MG medications and whether to change any of them before, during, or after pregnancy. Stopping MG medications during pregnancy is not recommended as it may worsen symptoms.
It's also important to stabilize the disease before conceiving, since about a third of people with MG have worse symptoms during pregnancy. For some women, a thymectomy—removal of the thymus gland, which is a part of the immune system—may help avoid MG symptoms during pregnancy. The surgery should be done well before a pregnancy is planned.
Patients who have unplanned pregnancies should alert their neurologists immediately to discuss any necessary changes or additions in medication. During their pregnancies, patients should report any MG flare-ups—new or worsening symptoms such as droopy eyelids, double vision, weakness in the arms and legs, or trouble chewing or swallowing—that may require additional treatment.
In rare cases, MG antibodies—not the condition itself—can be passed to babies during delivery.
Those newborns may have transient low muscle tone and weakness, be unable to breastfeed, and may need additional support in the first few days. Most recover within a few weeks and rarely develop the condition. Mothers with MG and their infants typically stay in the hospital for two days or more to be observed for symptoms of the disease. If babies develop symptoms such as difficulty sucking or breathing, they might be fed temporarily through a feeding tube in the neonatal ICU or get breathing assistance through a ventilator. The transferred antibodies are usually replaced by normal ones, and in some cases babies may get medication to speed up the process.
New mothers should talk to their neurologists about taking MG medications while breastfeeding and how to prevent flare-ups. Lack of sleep, for example, can trigger symptoms. Tips for conserving energy may include getting a disabled parking sticker or license plate to park closer to stores, using scooters at grocery stores or having food delivered, choosing smaller quantities of food (quarts instead of gallons of milk, for example) that are easier to lift, keeping frequently used items within easy reach, and even switching to electric toothbrushes or can openers.
Dr. Barnett-Tapia is associate professor of neurology at the University of Toronto.
