From http://en.wikipedia.org/wiki/Bilirubin

Bilirubin is essentially a waste product, formed when red blood cells die and haemoglobin is broken down. Haemoglobin is broken down within the macrophages to haem and globin; the haem is further degraded to Fe2+, carbon monoxide and bilirubin via the intermediate compound biliverdin. Since bilirubin is poorly soluble in water, it is carried to the liver bound to albumin. Bilirubin is made water soluble in the liver by conjugation with uridine diphosphoglucuronic acid or UDPGA. As part of bile, the soluble or “conjugated” bilirubin then passes through the common bile duct and is either temporarily stored in the gallbladder or passes right away into the gut. Some of the excreted bilirubin may be reabsorbed from the gut (entero-hepatic circulation). Bacteria in the intestines modify bilirubin to form stercobilinogen, causing the brown color of feces. The yellow colour of urine is a result of urobilin, another breakdown product of bilirubin.
In diseases where too much haemoglobin is broken down or the removal of bilirubin does not function properly, the accumulating bilirubin in the body causes jaundice.

Sarah was in the hospital for a couple days and we went to visit him regularly.

The NICU was actually a great learning experience the Nurses gave us training in caring for Max which we would find invaluable as time went on.