Autoantibodies in the mother will not get into the milk. Although it is
conceivable that an autoantibody can be IgA, it is not serum IgA which gets
into the milk. It is IgA specifically made by plasma cells, and these
require a special J chain in order to be absorbed into the alveolar cell.
Even if maternal autoantibody got into the milk, it wouldn't be absorbed by
the baby.  The mother should breastfeed and stop reading junk.

Jack Newman, MD, FRCPC