The authors report six cases of myasthenia gravis during pregnancy. Three patients experienced increasing severity of their disease and one death occurred in the puerperium. The infants were born with no evidence of neonatal myasthenia. The patients should be closely monitored during labor and puerperium. This disease is characterized by unpredictable exacerbations, and the association of myasthenia gravis and pregnancy increases the risk for the patient.