A consultant-led obstetric service was moved from Stafford to Royal Stoke University Hospital in January 2016.
The projected number of births is too low to operate a full unit, the report said. It added the hospital's midwife-led unit is an "important service".
The hospitals trust said it acknowledged findings from the report.
Read more news for Stoke and Staffordshire
NHS England, which published the review, said it commissioned it at the request of the government.
The report concluded it would not be possible to reinstate and safely maintain "a financially viable consultant-led obstetric service".
The projected amount of births at a County Hospital consultant-led obstetric unit would be "too low to provide adequate experience for staff to safely maintain their skills" or for trainees to complete studies, it stated.
Director of midwifery at the trust Karen Meadowcroft said she acknowledged the report findings.
She said: "I'm pleased that the Freestanding Midwife-led Birth Unit at County Hospital is recognised as a valuable and important service which offers mothers-to-be and their families a great birthing experience."
It would not be possible to safely return full maternity services to Stafford's County Hospital, a review has concluded.