paraphilic infantilism:

Or: infantilism , paraphilic condition in which sexuoerotic arousal is dependent on impersonating a baby in diapers and being treated as a baby . Autonepiophilia, a paraphilia of the stigmatic/eligibilic type, may be adjunctive to masochistic discipline and humiliation . The reciprocal paraphilic condition, playing the parent role with a partner who plays the infant, is nepiophilia.

ETYMOLOGY: From the Greek , autos , self, nepon , infant, and philia , attachment .