Four hours after delivery, a newborn develops poor feeding, lethargy, and mild respiratory distress. The mother's prenatal care was at another facility, and no records are available. The newborn's temperature is 37 ˚C (98.6 ˚F), pulse is 50/min, and blood pressure is 60/30 mmHg. Her lungs are clear to auscultation. There is no cardiac murmur. Electrocardiogram shows atrioventricular dissociation with otherwise unremarkable P waves and QRS complexes. An echocardiogram is normal.

Which of the following maternal diseases is the most likely cause of this infant's condition?