Neonatal Aspects of Maternal Myasthenia Gravis

Abstract

Background: Myasthenia gravis (MG) is a chronic autoimmune disorder characterized by skeletal muscle weakness, caused by antibodies targeting acetylcholine receptors (AChRs) at the neuromuscular junction. Acetylcholine receptor (AChR) antibodies can cross the placenta, affecting the fetus and leading to transient neonatal myasthenia gravis (TNMG) in 10 - 20% of newborns. Symptoms such as weak cry, feeding difficulties, respiratory distress, and hypotonia may be observed in affected infants. Objectives: The present study aims to evaluate the clinical outcomes in infants born to mothers diagnosed with MG. Methods: This retrospective cohort study included infants born to mothers with MG over a 15-year period. Maternal MG disease activity, pregnancy-related complications, and neonatal findings were reviewed from hospital records. The clinical characteristics of infants who developed transient neonatal MG were evaluated. Results: A total of 25 infants born to mothers diagnosed with MG were included in the study. The mean age of the mothers was 36.5 ± 6.7 (19 - 44) years, and 17 (68%) of the mothers were primigravid. Fourteen mothers (56%) had undergone thymectomy before pregnancy, and 21 (84%) were receiving medical treatment [prednisolone, intravenous immunoglobulin (IVIG), pyridostigmine]. Twenty-two pregnancies (88%) resulted in cesarean delivery. Among the infants, whose mean gestational age (GA) was 38.41 ± 1 weeks, 15 (60%) were female, and the mean birth weight was 3088 ± 512 (2000 - 4030) grams. Three infants (12%) were small for GA, and two (8%) were large for GA. None of the infants required resuscitation in the delivery room, and the median length of hospital stay was 3 (3 - 15) days. One (4%) infant required invasive and 2 (8%) required non-invasive mechanical ventilation. Two of them (8%) developed poor feeding and hypotonia. The infant who required invasive mechanical ventilation was treated with pyridostigmine. Symptoms of transient neonatal MG began to improve by the second day of treatment. The treatment was completed within 10 days for the infant. No infant deaths occurred. Conclusions: Transient neonatal MG may present with a range of clinical manifestations, from mild hypotonia to severe respiratory failure. Appropriate clinical monitoring and treatment of pregnant women and close clinical observation of the infants may improve neonatal outcomes.