The query regarding breastfeeding and the mother and baby who are
incompatible with regard to red blood cell type (ABO or Rh erythroblastosis)
raises and important question that answered many years ago.  Breastfeeding
has no effect on the rate of red cell hemolysis in the baby with
erythroblastosis and there is no contraindication to breastfeeding even when
the Coombs test is positive, incidating that the mother has transferred
antibody from her blood into the fetus' blood.  Of course, hemolysis
increases the bilirubin load for the baby and may exaggerate the level of
bilirubin in the breastfed baby later in the newborn period (after about 5 -
7 days) when breastmilk jaundice normally begins.  The may be need,
occasionally, as in this baby to temporarily interrupt breastfeeding to let
the bilirubin decline.  This happens within 24 hours and the mother can then
resume breastfeeding.  The bilirubin may increase a little when
breastfeeding resumes, but usually only a few milligrams.  It must be
checked regularly, however, until it stops increasing because there are rare
babies whose bilirubin level jump very high.  In general, breastfeeding does
not need to be interrupted unless the serum bilirubin level is over 20
mg/dl.  But, there is no reason not to resume breastfeeding once the level
has dropped down.
                                                Larry Gartner