Three cases of pregnancies complicated with myotonic dystrophy type 1

Myotonic dystrophy type 1 (DM1) is a neuromuscular disorder caused by trinucleotide repeat expansion. Pregnancies with DM1 are prone to complications, and congenital DM1 often presents with severe symptoms at birth. This report reviews three cases of congenital DM1 and explores potential predictive factors for both maternal and fetal DM1. Among the three cases, two were diagnosed with DM1 either before or during their current pregnancy. Although no common features were observed across all cases, elevated serum creatinine phosphokinase (CPK) levels were noted in two cases diagnosed with DM1 before labor. Despite all cases being congenital DM1, biophysical profile scores were normal. Severe congenital DM1 should be considered if unexpected neonatal asphyxia occurs even when typical signs such as polyhydramnios or abnormal fetal heart rate are absent. Maternal DM1 diagnosis was supported by elevated serum CPK, muscle weakness, and family history.