Staffing at a neonatal unit that reported a "higher than usual" number of baby deaths was "inadequate", a report said.
A review by the Royal College of Paediatrics and Child Health said no "definitive explanation" was found for an increase in mortality rates at the Countess of Chester Hospital.
There were 13 unexplained deaths between January 2015 and July 2016.
The hospital said neonatal intensive care remained suspended.
The review recommended increasing staffing and improving leadership.
It found "significant gaps" in medical and nursing rotas, "poor decision-making" and "insufficient senior cover".
'No single cause'
Medical staffing was "sufficient" for a special care unit but "inadequate" for high dependency, the report said.
Transport services in Cheshire and Merseyside were "under-resourced", it added.
The Countess of Chester, which looks after about 400 babies a year, stopped providing care for babies born earlier than 32 weeks in July last year.
Any women expected to deliver earlier were transferred to a neighbouring facility.
The hospital said that while "no single cause" had been found to explain the increase in neonatal deaths on the unit, the change to admissions would remain in place "until we are certain we have acted on all the recommendations in the review".
- Hold external reviews of all 13 deaths
- Improve staffing levels
- Strengthen arrangements for investigating deaths
- Improve leadership
- Appoint two additional consultants
- Hold unit-wide debriefs for neonatal deaths
- Appoint a "Children's Champion" on the board
- Give "early warning" calls to transport team
The review team said that there were no "obvious factors" linking the deaths. It recommended that all 13 be reviewed individually.
Ian Harvey, medical director at the hospital, said it had "acted swiftly" and those reviews had now been completed.
"When we speak with parents we can now share full and accurate information, on an individual basis. We are desperately sorry for any distress or upset this review has caused. We know those families affected have been through so much already," he said.
Baby deaths at the facility
- 2009 - 3
- 2010 - 1
- 2011 - 3
- 2012 - 3
- 2013 - 2
- 2014 - 3
- 2015 - 8
- 2016 - 5
The review said there was an "enthusiastic" group of paediatricians complemented by a "well-led and supportive" team of nurses.
There was "robust" training and "extremely positive" relationships amongst various teams in the neonatal unit, it added.
The Countess of Chester Hospital NHS Foundation Trust said families left bereaved by the loss of their babies had always been its "primary concern", and it was already working to implement the Royal College's recommendations.
Chief executive Tony Chambers said: "It must have been devastating for them to lose their baby, and then face a period of not knowing.
"We are now able to share everything that we understand about what has happened here and our thoughts are with them."