Families who lost babies due to errors in maternity care in Nottingham have met the health secretary, Sajid Javid.
They have voiced their concerns about the independence and speed of an ongoing review.
So far, 544 families have contacted the investigation into maternity services at the Nottingham University Hospitals NHS Trust (NUHT).
The review is examining cases over a 15-year period, from April 2006 until October 2021.
A total of 71 staff from the trust have also contacted the inquiry.
Jack Hawkins, a former consultant at the trust, became a whistleblower after his daughter Harriet was stillborn in 2016.
A series of errors during Mr Hawkins' wife Sarah's pregnancy were found to have caused Harriet's death.
"Not only did she die but we were blamed. They denied that we'd had contact with them," Mr Hawkins previously told Sky News.
The couple had to show phone records to prove they had called the hospital with concerns.
"Harriet was basically stuck and they had said Sarah wasn't in labour," he said.
"We went in and then just out of the blue they said your baby's dead."
At the time, Mr Hawkins was a consultant in acute medicine at the trust and Sarah was a physiotherapist.
They no longer work there after a lengthy battle that ended with the trust admitting liability and negligence.
The couple were awarded a £2.8m settlement.
They were among a group of families who wrote to the health secretary last month asking for the investigation into maternity services in Nottingham to be taken over by Donna Ockenden, the independent midwife whose report revealed more than 200 babies died unnecessarily at the Shrewsbury and Telford NHS Trust.
The review in Nottingham was commissioned by the local clinical commissioning group, along with NHS England and NHS Improvement and was due to be carried out by former NHS trust chair Julie Dent.
However, on Wednesday, she announced she has declined the role due to "personal reasons".
Mr Javid said it is "crucial" to have the "best possible leadership" in place to carry out the review and he is working to ensure "no families have to go through the same pain again".
"My sympathies remain with all those tragically affected by these harrowing failures and I acknowledge the courage and strength shown by all," he said.
In the letter to the health secretary, the families wrote: "Historically there have been reviews, nothing has changed.
"If families are to be safeguarded, real and impactful intervention is required."
After meeting the Mr Javid, the families said a "first significant step" has been taken to ensure the "protection of babies and mothers from death and harm in the future".
"It is the first time that families have been properly listened to by senior healthcare professionals since Jack and Sarah Hawkins originally whistle blew the problems in maternity care at NUHT back in 2016," they said in a statement.
Mother visited hospital four times - but her baby died two days after birth
Last week an inquest into the death of two-day-old Quinn Parker at the trust in July 2021 heard that his mother had gone to hospital four times with bleeding in the late stages of her pregnancy but she wasn't informed about the risk of placental abruption.
His parents, Ryan Parker and Emmie Studencki, said they have "serious concerns" about the care they received.
The inquest is due to conclude next week.
In 2020, maternity services run by NUH were rated inadequate by the Care Quality Commission.
A reinspection in March saw NUH issued with a warning notice.
The inspection found an increase in stillbirths and some midwives acting outside of their competence. It also highlighted issues with understaffing.
A spokesperson for Nottingham University Hospitals said: "We will continue to engage fully with the independent review and remain committed to improving local maternity services using feedback from the review as well as local families and NHS partners."