Granted the rapid rise in the bilirubin is worrisome.  With a positive
coombs, the baby almost certainly has hemolysis.  But there is no reason
to prefer formula over breastfeeding.  I hope the reason the
pediatrician is saying formula is that more fluid can be given, rather
than "breastmilk jaundice".  The baby should be breastfed.  The mother
should at least be pumping to establish her milk supply and so the baby
can get some the same way he is getting the formula, so that she may be
able to breastfeed when the bilirubin is under control.

Personally, I would not think that a few minutes out of the incubator
every few hours to breastfeed will change the course of the illness one
iota.  I would also prefer an iv to bottle feeding or gavage feeding.

Jack Newman, MD, FRCPC