Characterizing Perinatal Treatment Patterns and Outcomes in Myasthenia Gravis.

INTRODUCTION/AIMS: Studies on pregnancy in myasthenia gravis (MG) are limited by small sample sizes or examine a limited number of outcomes. The objective of this study was to estimate the prevalence of perinatal and infant outcomes and characterize perinatal treatment patterns in MG. METHODS: We conducted a retrospective cohort study in Merative MarketScan Commercial Claims and Encounters (CCAE) and two other United States health insurance claims databases. Pregnancies in females aged 18-49 years were identified and maternal and infant records were linked. MG was defined by ≥ 1 inpatient or ≥ 2 outpatient diagnoses within a 365-day period. The prevalence of six perinatal outcomes was calculated in the MG and total populations. Treatments were summarized by class. RESULTS: In pregnancies from CCAE between 2000-2023, preeclampsia (10.7% vs. 7.1%), Cesarean section (42.9% vs. 36.7%), preterm birth (18.0% vs. 9.9%), and small for gestational age (4.3% vs. 1.7%) were more frequent among MG (n = 900) than the age-adjusted total population (n = 5,185,726). Lack of treatment for MG was common across the perinatal period: 54.3% were untreated in the 6 months preconception, 61.2% in pregnancy, and 57.8% in the 6 months postpartum. Of those taking acetylcholinesterase inhibitors or corticosteroids in pregnancy, 21.8% and 33.1% had not been taking them before pregnancy, respectively. DISCUSSION: MG was associated with a greater prevalence of certain perinatal outcomes, occurring in both mother and infant. In parallel, though most patients did not receive treatment in pregnancy those who did showed variation over time, suggesting a potential need for this population.