A whistleblowing letter has been sent to inspectors and a local newspaper by maternity care staff at a hospital.
Midwives at West Suffolk Hospital in Bury St Edmunds said they were "exhausted and broken" and claimed the unit was "consistently short staffed".
A report into an alleged "witch-hunt" of previous whistleblowers at the hospital is due later this year.
The West Suffolk NHS Foundation Trust, which runs the hospital, said it provides a "safe and caring service".
The anonymous letter was sent to the Bury Free Press, the Care Quality Commission (CQC) and the hospital trust.
It claimed the midwives had spoken out because standards of care had fallen sharply.
Staff were "under extreme pressures all the time, which has left them fed up, exhausted and burnt out", it said.
'Working exceptionally hard'
The letter continues: "The unit essentially runs on the goodwill of staff.
"However, due to the atmosphere at work being so unpleasant and morale being so low, our goodwill is rapidly running out.
"It should not be accepted or tolerated for us to be forced into giving unsafe care entirely due to unsafe staffing."
The head of midwifery at the trust, Karen Newbury, said: "We are working exceptionally hard to recruit additional midwives and we are very grateful for the flexibility and dedication of our staff in ensuring that we provide a safe and caring service."
She added the trust had recruited more midwives "to provide flexible and experienced support to our maternity teams".
The CQC confirmed it received a copy of the letter and was waiting for the outcome of the trust's investigation of the concerns raised.
"We will use the information received as part of our ongoing monitoring of the trust," a spokeswoman said.
The hospital and its maternity unit were rated as "requires improvement" by the CQC in June.
In 2019, private firms were engaged by the hospital to analyse fingerprints and handwriting as it sought to identify the author of a letter sent to the husband of a deceased patient.
The Doctors' Association described the hospital's attempt to find the author of the letter a "witch-hunt".