Transient Neonatal Myasthenia Gravis in a Newborn Infant Presenting to an Emergency Department.

A four-day-old female born full term via uncomplicated vaginal delivery presented to the emergency department with poor oral intake. There was a significant maternal history of myasthenia gravis requiring pyridostigmine and intravenous immunoglobulin infusions five days per month. It was suspected that the patient had transient maternal acetylcholine antibodies causing the weakness and poor oral intake. The patient was admitted to the neonatal intensive care unit for further evaluation and management. Laboratory evaluation revealed elevated acetylcholine receptor antibodies at 2.69 nmol/L, which confirmed transient transfer of maternal antibodies. After a six-day hospitalization, the patient had improved oral intake, appropriate weight gain, and resolution of her weakness. The patient was safely discharged home.