a general term, which seems to have been applied by the Romans to those divinities who were believed to assist women at the time when they were giving birth to a child. (Quos putabant praesidere parientium nixibus, Fest. p. 175, ed. Müller; Ov. Met. 9.294; Nonius, p. 57.) Before the cella of Minerva, on the Capitol, there were three statues, which were designated as Dii Nixi.
[L.S]A Dictionary of Greek and Roman biography and mythology
Smith, William
A Dictionary of Greek and Roman biography and mythology. William Smith, LLD, ed. 1890