The two, a 45-year-old woman and a 57-year-old man, were detained late Tuesday in the central city of Brasov.
The Italians allegedly reached an agreement earlier this month with a nine-month-pregnant Romanian woman to register her baby under their names at birth, so they could leave the country with the newborn.
The Romanian gave birth in a private clinic in the eastern city of Bacau, where she was registered under the name of the Italian woman, local prosecutors said.
Prosecutors have asked for the Italians to be held in pre-trial detention for 29 days. A court will decide on the request later Thursday.