We have to understand the difference between chicken pox and shingles.
When someone has shingles (assuming it is shingles), what they've got is
a reactivation of a previous chicken pox infection which may have
occurred decades before.  It means the person is immune, though the
shingles may cause chicken pox in contacts who are not immune.  (Contact
is by touch, by the way).  This means that the baby will be born with a
ton of antibodies from the mother, and there is *no* reason to limit
breastfeeding to the unaffected side.  Furthermore, breastfeeding comes
through again, the milk will contain antibodies against chicken pox,
fatty acids (which kill encapsulated viruses such as chicken pox).  Even
if the shingles reactivate, which is unlikely, the mother should not
limit breastfeeding.

Jack Newman, MD, FRCPC