The implant does not cause any problems for breastfeeding or the baby. Nor
does breastfeeding cause problems for the implant. The mother may not
produce enough milk on the implanted side, because it sounds as if the
breast did not develop, but that does not mean she won't for sure.  Watch
and wait.

Any surgery with a periareolar incision may decrease milk supply, so if
that's what she had on the good side, she should be very angry with the
surgeon.  Otherwise, there should be no effect.

Jack Newman, MD, FRCPC