The health secretary has ordered an investigation into the deaths of a number of babies at an NHS trust in the Midlands, after seven of them were judged to have been avoidable.

Jeremy Hunt made the move after bereaved families and the local coroner criticised the quality and safety of maternity care at the Shrewsbury and Telford Hospital NHS trust. He has asked NHS England and NHS Improvement to look into an undisclosed number of deaths at the trust in recent years, amid concern that some were not properly investigated at the time.

The BBC said it had obtained details of at least nine suspicious deaths that occurred at the trust between September 2014 and May 2016, seven of which were later deemed to have been avoidable if the newborns had received better care.

Five of the deaths involved apparent failures by staff to correctly monitor a baby’s heartbeat.

Dr Edwin Borman, the trust’s medical director, said the rate of baby deaths at the trust – which handles 4,700 deliveries a year – was no worse than anywhere else in the NHS.

However, he told BBC News: “In the case of foetal heart monitoring, we have identified a number of cases where learning has not been fully implemented. We’ve put systems in place to make improvements.”

John Ellery, the coroner in the June 2016 inquest into the death of Kye Hall at Telford’s Princess Royal hospital, said errors by staff had contributed to the baby boy’s death.

“His death was caused or contributed to by failings at the Princess Royal hospital, Telford, namely a failure to reclassify Kye’s mother as a high-risk case on two occasions and a failure to auscultate [listen to] his foetal heart rate at two critical times prior to delivery,” the coroner said.

Kye was born on 15 August 2015, but he died four days later as a result of hypoxic ischaemic brain injury and birth asphyxia, or serious oxygen deprivation.

The trust accepted during the inquest that some recordings of Kye’s heart rate when he was still in the womb were not taken or written down, and that his mother, Kate Anson, could have been referred to the consultant-led maternity unit when her blood pressure dropped.

Last week, an inquest into the death of a one-day-old girl, from a group B streptococcus infection while in the trust’s care, found she could have lived had she received better medical attention. The trust accepted that Pippa Griffiths would probably have survived if staff had spotted the infection earlier.

Pippa was born at home on 26 April 2016. When her mother, Kayleigh, rang the maternity unit at 6.30pm to voice concern about Pippa’s feeding, staff reassured her. She said she called again at 2.55am the next day to report brown mucus, although midwife Claire Roberts said she did not remember the baby’s mother saying that.

Sarah Jamieson, the trust’s head of midwifery, said afterwards: “We are truly sorry that we were unable to provide the appropriate care that would have prevented Pippa’s death.”

Maternity services at the trust were strongly criticised last year in an inquiry, commissioned by NHS England, into the death of a baby girl, Kate Stanton-Davies, in 2009.

Her mother, Rhiannon, said: “Look at the failings, learn from them, move on. To not do that, they haven’t just killed my daughter, but they have disregarded the value of her life, her memory.”

The inquiry found a “lack of a safety culture” in the maternity unit at the time. It also found staff had not been held accountable for their failings related to Kate’s death, and that lessons needed to improve patient safety had not been learned.

The nine suspicious deaths include those of twins Ella and Lola Greene, who were stillborn in 2014 after staff failed to correctly read and interpret their heart rates. The trust also accepted other inquest findings that poor foetal heart monitoring was a factor in the deaths of Graham Scott Holmes-Smith in 2015 and Ivy Morris in May 2016.

Other deaths under examination include that of Oliver Smale in 2015. The coroner said his death could have been prevented if he had been born earlier by caesarean section.

The Department of Health said: “Earlier this year, the health secretary asked NHS regulators to undertake an investigation at Shrewsbury and Telford NHS trust in light of disclosures that in a number of tragic cases standards of care fell far below those that parents would expect.”