Lupus may result in the baby developing congenital heart block.  This
may result in cardiac failure.  The problem may resolve or be permanent.
As far as I know lupus is *not* associated with cardiac problems such as
holes in the heart.

Sick babies do not need breastmilk (and breastfeeding) less.  They need
it more.  There is no evidence the mother with mastitis will pass
infection on to the baby.

Jack Newman, MD, FRCPC