Hilchos Lashon Hara chapter 8, section 3

Lashon hara applies even when one speaks of a minor. For example, to speak disparagingly of a minor raised by someone in his home. For this may lead to him being thrown out. The same applies to any harm or distress caused to a minor. (If the facts are well known, see above chapter 2:3,9, and volume II 2:3). If one wants to save people from harm done by the minor or to improve his behaviour, this is permitted. But one must known in advance that the story is true and not be quick to rely on what one heard from others as we explain later in chapter 10. One must also see what might result from one’s speaking, for unwanted things often result in such incidents.