A male infant is born via vaginal delivery at 29 weeks’ estimated gestation with a birthweight of 1,490 g to a 22-year-old gravida 1, para 1 woman who presented with preterm labor. No maternal risk factors are identified; all maternal prenatal laboratory findings are negative. Group B Streptococcus carrier status is unknown and no intrapartum antibiotic prophylaxis or betamethasone had been administered because it was a precipitous delivery. The infant’s Apgar scores are 8 and 9 at 1 and 5 minutes, respectively. Physical examination findings are normal, with mild retractions. The infant initially undergoes intubation for surfactant therapy and is started on broad-spectrum antibiotics to rule out sepsis and total parental nutrition (TPN). One day after birth, he is weaned to continuous positive airway pressure and gradually to room air. Routine echocardiography shows a large patent ductus arteriosus which is treated with acetaminophen with subsequent closure and trivial aortic insufficiency on repeat follow-up echocardiography. The infant continues to receive TPN and partial oral feedings until 18 days after birth, when he starts having bloody regurgitation. Because of a concern for necrotizing enterocolitis (NEC), broad-spectrum antibiotics are initiated and oral feeds are suspended. Feedings are then restarted, with resolution of NEC. Shortly after, at about 1 month of age, he develops generalized edema with hypoalbuminemia of 3.1 g/dL (31 g/L), which improves with a high protein diet and furosemide. He receives 3 packed red blood cell infusions for anemia, with a hematocrit below 28%, after which he develops cellulitis from an intravenous infiltrate that resolves with a course of vancomycin. Concurrently, the total and direct bilirubin levels are increased at 5.41 mg/dL (92.5 μmol/L) and 0.4 mg/dL (6.8 μmol/L), respectively. Bilirubin level trends are observed and are shown in Table 1. No jaundice or acholic stools are seen nor is …