eMedicine Specialties > Obstetrics and Gynecology > Medical Problems in Pregnancy

Myasthenia Gravis and Pregnancy: Follow-up

Author: Idan Sharon, MD, Consulting Staff, Departments of Neurology and Psychiatry, Cornell New York Methodist Hospital; Private Practice
Coauthor(s): Jaclyn P Wilkens, Hofstra University
Contributor Information and Disclosures

Updated: Feb 9, 2010

Follow-up

Further Inpatient Care

• Follow-up consists of evaluating patients for adverse effects of pharmaceuticals and preventing infection. Observing the patient for signs of respiratory deterioration is necessary. The postanesthetic period is very important because postpartum exacerbation is common. Arterial blood gases should be checked often; thus, a surgical ICU is the best place for postoperative patients with myasthenia gravis.
• Rest periods should be emphasized in the months after delivery. Caring for a newborn is difficult, and maternal exhaustion may occur. The disease course is variable and unpredictable during pregnancy and after delivery. One pregnancy without exacerbations does not necessarily mean that future pregnancies carry no risk. Pregnancy can lead to many complications; therefore, the physician must be vigilant.

Complications

• Some rare problems may occur during pregnancy. Maternal complications are discussed as follows: 
  • In 2000, Ellison and colleagues reported a rare case of bone marrow suppression in a patient who experienced leukopenia and thrombocytopenia during all 3 of her pregnancies.¹⁸
    • The patient's third pregnancy was the most serious. Her platelet count was 48 X 10⁹/L, and her WBC count dropped to 1.5 X 10⁹/L at 35 weeks' gestation. She improved after receiving 65 mg of human immunoglobulin (1 mg/kg for 2 d). Labor was induced, and she delivered a boy. Interestingly, 1 day after each delivery, her platelet and WBC counts increased. On the third postnatal day, her platelet count increased to 128 X 10⁹/L from 82 X 10⁹/L after immunoglobulin transfusion, and her WBC count increased to 2.5 X 10⁹/L from 2.2 X 10⁹/L.¹⁸
    • Bone marrow suppression has been observed in other pregnant patients with myasthenia gravis. In 1992, Igarashi et al reported that suppression could be due to megakaryocyte colony-forming unit suppressive factor produced by autoimmune mechanisms.¹⁹
  • Some exacerbations can be linked to the anxiety and physiological stress of pregnancy. Hypoventilation is a risk during pregnancy because respiratory muscles are weakened from myasthenia gravis. Also, the lungs do not become fully inflated because the diaphragm is elevated during pregnancy. Approximately 20% of patients experience respiratory crises that require mechanical ventilation. This is one of most severe complications.
  • Infections due to decreased immunity play a very important role in the exacerbation of myasthenia gravis during pregnancy.
  • Labor may be complicated. Although smooth muscle is not affected by autoantibodies and the uterus is not compromised, the second stage of labor involves striated muscle. The patient may become exhausted during labor and may require assistance. Operative vaginal delivery has been recommended.
  • In 1979, Duff described an association between myasthenia gravis and preeclampsia.²⁰ They observed preeclampsia in 3 patients and reasoned that altered immune status could be an etiologic factor in preeclampsia. Preeclampsia may also be problematic from a pharmacological standpoint because magnesium sulfate is contraindicated in myasthenic patients.
  • In 2007, Mueksch and Stevens presented a case of myasthenia gravis misdiagnosed as eclampsia during postoperative complications.²¹ A pregnant 21-year-old woman arrived at the emergency room with a prolapsed umbilical cord at 40 weeks, reporting no abnormalities in prior pregnancy or general medical history. Multiple episodes of seizure activity were observed in the PACU in the 24 hours following delivery by cesarean section, prompting diagnosis of eclampsia. Seizure activity continued following treatment with intravenous magnesium sulfate, as the patient experienced further respiratory distress. Edrophonium was administered during a neurology consult, revealing myasthenia gravis as the underlying condition, and magnesium sulfate treatment was stopped. The patient improved with plasmapheresis treatments. In the event that eclampsia does present in the pregnant patient with myasthenia gravis, phenytoin is the currently accepted method of treatment.
• Not only is the mother at risk, her baby also faces significant risks, including neonatal myasthenia gravis, prematurity, severe malformation, and death.
  • Rates of neonatal myasthenia gravis are as high as 10-20%. Affected babies show respiratory distress and inadequate suck. Babies are affected by transient myasthenia, which is self-limited and lasts approximately 3 weeks. This is due to the transplacental transfer of antibodies. This is puzzling because no close correlation exists between maternal disease severity and neonatal myasthenia, and no correlation exists between the occurrence of neonatal myasthenia gravis and maternal anti-AChR antibody titers. These unpredictable results could be due to the protective role of alpha-fetoprotein in neonatal myasthenia gravis. Alpha-fetoprotein has been shown to inhibit the binding of myasthenia gravis antibody to its receptor.
  • More severe neonatal problems have been reported, including death from malformations attributable to myasthenia gravis. In 1991, Carr and colleagues reported that the most common fetal abnormalities are pulmonary hypoplasia and arthrogryposis.²² They reported the case of a patient whose 2 previous births were followed by neonatal death due to malformation. During the patient's third pregnancy, they decided to decrease her antibody titer, which was very high (400 nmol/L), by using plasmapheresis and prednisone. They found that fetal breathing increased when antibody levels were low, and it decreased with increasing antibody titers. The presence of abnormalities in this case coincided with the presence of AChR antibodies of high avidity. The hypothesis was that these antibodies inhibited fetal diaphragmatic motion, which resulted in a lack of stimulation of normal fetal lung development.
  • Behin et al discussed the rare case of severe neonatal myasthenia gravis occurring despite the myasthenic mother presenting with a mild case.¹⁰ Mild symptoms led to myasthenia gravis diagnosis of the mother 4 years prior to birth of the myasthenia gravis neonate. During pregnancy, polyhydramnios and decreased fetal mobility were observed on a sonogram at 33 weeks. Hypotonia, stridor, and inadequate sucking were observed at the time of birth, and respiratory failure requiring ventilation occurred within hours. Both mother and baby tested negative for anti-AChR antibodies and positive for anti-MuSK antibodies. The mother's symptoms did not worsen after delivery. The child experienced multiple motor delays that gradually improved over the first 23 months of life.
  • Prematurity is a concern. In 1991, Plauche compiled the results from various studies and found that premature delivery occurs in approximately 36.5% of cases.⁴
  • Breastfeeding by the mother with myasthenia gravis is safe if she is following a treatment course that utilizes pyridostigmine or corticosteroids; however, mothers with myasthenia gravis being treated with azathioprine, methotrexate, mycophenolate mofetil, or cyclophosphamide, as well as mothers of newborns with myasthenia gravis should not breastfeed.⁹

Miscellaneous

Medicolegal Pitfalls

• Because many medications can adversely affect patients with myasthenia gravis (MG), the following drugs should be avoided:
  • Narcotics
  • Tranquilizers
  • Barbiturates
  • Inhalation anesthetics (ie, halothane, trichloroethylene, ether)
  • Magnesium and lithium salts
  • Penicillamine
  • Beta-adrenergic agents
  • Quinidine
  • Aminoglycoside antibiotics
  • Colistin
  • Neomycin
  • Tetracycline drugs
  • Lincomycin
  • Polymyxin
  • Quinacrine
  • Chloroquine

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