A 3-day-old boy at 37 weeks' gestational age is brought to the emergency room by his mother after the baby presented with jaundice. The mother describes her baby had jaundice on the first day after birth, although he appears no other symptoms. His vital signs are normal and his respiratory and abdominal examinations are unremarkable. He has moderate jaundice. A blood test reveals bilirubin level of 290 umol/L . What is the best course of action in this situation? ( )