Definition of "prejudicially"

In this case, however, the parent's health will chiefly suffer, if she persevere in nursing; this, however, will again act prejudicially to the child.

1840, Thomas Bull, M.D., The Maternal Management of Children, in Health and Disease.‎

"But surely that will prejudicially affect the rumor you were going to spread, sire?"

1628, Alexandre Dumas, Père, Ten Years Later‎