A baby died after suffering brain damage when he and his mother were exposed to a "gross failure of basic medical attention", a coroner has ruled.

Noah Tyler died 10 months after a midwife overseeing his birth at the University Hospital of Wales in Cardiff failed to take action though the baby's heart rate was worryingly high. He was deprived of oxygen and his mother, Colleen Tyler, 31, could also have died during the birth, the hearing was told.

Recording a narrative verdict, the coroner, Mary Hassell, said: "I am very, very concerned with the circumstances surrounding Noah's death. What struck me very forcibly was that we might today be dealing with two deaths rather than one. Noah and his mother suffered gross failure of basic medical attention." She said Noah died of natural causes "contributed to by neglect".

During the inquest, the midwife Julie Richards said she failed to take the necessary action after noticing that Noah's heart rate was high. She said: "With hindsight I would have acted differently – I don't know if I looked at the heart scan properly. If I had I would have sent her immediately upstairs to see specialist doctors."

The inquest in Cardiff heard Richards, who had 13 years experience of delivering babies, is no longer working as a midwife.

Noah's mother had told the hearing she was "tortured" by what had happened during the birth in February last year. She said: "I asked if I needed a doctor but they told me there was no need to get the doctors involved because they would just cut me. In the end I told them they should do what they needed to to get my baby out."

Tyler told the hearing she knew instantly that something was wrong. "I was told I would hear him cry when they got him out but I didn't hear anything. He was very white, not how I expected him to look.

"No one said anything and I was left feeling confused. I was in a state of shock – I thought: 'This cannot be happening. I expected to be holding my baby by then but he wasn't there.'"

She continued: "I knew from the doctor's face that something terrible had happened. I keep replaying the birth in my head and torturing myself. What if I could have done anything different to save Noah, the thoughts just go on and on?"

Speaking outside the coroner's court following the verdict, Noah's father, Hywel Tyler, of Caerphilly in south Wales, said: "It is because of the failings of one person that my boy isn't here any more and there's no reason why he shouldn't be.

When the coroner said this could have been an inquest around two deaths it hit me like a tonne of bricks."

Paul Hollard, interim chief executive of Cardiff and Vale University Health Board, said: "I would like to offer our sincerest sympathies and apologies to Noah's family, who we continue to support in any way we can.

"We are deeply sorry for what happened to Noah and Mrs Tyler, and this case has made us even more determined to constantly review and improve our services to ensure we provide the excellent care for mums and their babies that they have a right to expect.

"We would like to reassure the public that we have thoroughly investigated what happened in this tragic case and have taken a number of clear and decisive actions, including dismissing the midwife involved.

"The improvements we have made to our care were highlighted by the Coroner and she also acknowledged the hard work of staff at the unit. We will wait for the Coroner's detailed findings so that we can review them and take any further action necessary.

"This has been a very tragic case and everyone at the health board would like to extend their condolences again to Mr and Mrs Tyler and their family and offer any support we can."