A 48-hour-old newborn girl develops bilious emesis and refus…

A 48-hour-old newborn girl develops bilious emesis and refuses to breastfeed. She was born via C-section at 38 weeks due to nonreassuring fetal heart rates to a primigravid mother who received inconsistent prenatal care. Prior to the vomiting, the neonate was voiding urine normally but has not yet passed her first stool. The patient’s mother states she has no significant medical history but that her father died from pneumonia at the age of 44. The patient’s vitals are stable and within normal limits. Examination shows abdominal distension with palpable intestinal loops. Rectal examination shows normal tone and no stool in the rectal vault. X-ray of the abdomen shows air-fluid levels and small bowel dilation, suggesting a ileus. Which of the following is the most likely cause of this newborn’s condition?