Hi J.! Congrats on your new little one! I remember the jaundice with both of mine and one was formula fed, the other fully breastfed. I consulted my LLL book, The Womanly Art of Breastfeeding. I'll try to paraphrase for you, but if you can get this book it has a great chapter all about jaundice in the breastfed baby and how normal it is, even the kind caused by incompatible blood.
Called pathological jaundice, caused by rh or abo blood incompatibilities. Both are quite common. Breastfeeding can and should continue even if treatment is needed and often helps to reduce the jaundice. A bilirubin level of over 25 is considered high after the first 48 hours from birth. Brain damage from extremely high bilirubin levels is very rare in non preemies.
"It is important for parents to remember that complications or damage from high bilirubin levels are very rare."
"Frequent breastfeeding itself will help lower bilirubin levels and should be considered an important part of the treatment plan, if any is necessary. Continued monitoring of the baby's condition along with efforts to encourage baby to nurse often and effectively may be all that is needed."
If you would like the info the book has on phototherapy or bililights, let me know. I also remember putting the bassinet by the window so sun could shine in on baby for a little while every day which helped!