Sheffield Teaching Hospitals NHS Foundation Trust needs to make significant improvements according to a 230-page report by care quality inspectors.
The Trust's overall rating has dropped from "good" to "requires improvement", with particular concern over maternity services at the Jessop Wing.
Opening more than twenty years ago, Jessop Wing wards in Sheffield see around 7000 babies born every year.
The Care Quality Commission (CQC) arrived unannounced in October to follow up on a visit six months earlier that identified safety concerns. Inspectors say services have not shown sufficient change from March 2021 and it remains inadequate.
Among other requirements to improve care, the report said that Maternity services "must ensure that delays to induction of labour is significantly reduced".
The Trust say that it has already made significant improvements. CEO Kirsten Major said: "Both myself, the whole leadership team and board their first reaction was to be devastated and then very quickly to take on board the findings of the report and make sure we put plans in place to improve."
It adds that over five hundred new nurses have been recruited after the CQC highlighted a lack of staff.