Myasthenia gravis and pregnancy

Pregnancy is certainly an option open to patients with myasthenia gravis. Preconceptional counseling is the ideal, with the goal of discontinuing or reducing corticosteroid medications in patients requiring those agents. Alterations in physiology will require ongoing and careful assessment of the pregnant myasthenic or cholinergic crises. Antenatal testing for fetal well-being may be difficult to interpret. A small number of fetuses with fetal myasthenia gravis will be diagnosed by ultrasound. Attempts may be made to decrease the amount of circulating antibody crossing to the fetus. Interventions may include starting or increasing corticosteroid therapy, therapy with azathioprine, or plasmapheresis. Thymectomy is usually not performed during pregnancy. The intrapartum period will increase fatigue in the mother and may precipitate a myasthenic crisis. Epidural anesthesia is currently the agent of choice for decreasing pain and fatigue. An outlet forceps or vacuum delivery will shorten the second stage of labor in those patients who are unable to push repetitively. Cesarean delivery is preferably avoided in those patients at risk for pulmonary and thrombo-embolic complications. Narcotic and sedative medications may be used in the presence of careful and continuous assessment; they may increase respiratory and muscular symptoms. The postpartum period may be associated with an increase in exacerbations. Support services may help to eliminate or to reduce potent stressors during this time. Medication dosages may need to be adjusted as the mother's body returns to her prepregnant state. Transient, neonatal myasthenia is seen in up to 21% of maternal myasthenic cases, even in those patients with no detectable circulating antibody.