Review Question - QID 102770

A 3-day old baby boy is brought to the pediatrician by his mother for his first post-natal visit. He was born via vaginal delivery at 39.2 weeks with Apgar scores of 7 and 9 at 1 and 5 minutes, respectively. The mother's pregnancy was uncomplicated. He stayed in the well-baby nursery for two nights and was discharged without incident. On physical exam, the neonate appears lethargic with a soft, open fontanelle and soft abdomen. His skin is notable for a yellowish tinge (Figure A). Mom is exclusively feeding him breastmilk for 5-10 minutes every 4 hours. At birth his weight was 7lbs 6oz and his current weight is down to 6lbs 8oz. What process is most likely causing his skin yellowing?