An initiative allowing rapidly deteriorating patients and their families to seek a second opinion will play a role in "changing the culture of the NHS", Merope Mills has said.
Ms Mills began her campaign for "Martha's rule" after her daughter Martha, 13, died of sepsis in 2021.
Speaking on BBC R4's Today programme, Ms Mills said it was "encouraging" to see 143 NHS hospitals sign up to the scheme.
The rule change will challenge a "culture of deference" towards doctors in some hospitals, Ms Mills said.
Martha's rule will allow patients and families to seek an urgent review if their condition, or the condition of a loved one, is deteriorating and they feel their concerns are not being listened to.
They will be able to call an internal phone number and request a second opinion from a critical care outreach team.
Clinicians will also record daily insights and information about a patient's health directly from their families.
"We hope it will do an immense amount of good by improving communication and encouraging doctors just to be more open and to listen to patients more carefully," Ms Mills said.
"We also want patients to be able to challenge this culture of deference that we have, this sense that [the] doctor always knows best, because I personally have come to believe that a more equal relationship is a safer relationship," she said.
Ms Mills added that she was not always confident her campaign for Martha's rule would be successful. "The medical world is incredibly change-averse," she said.
Thirteen-year-old Martha was admitted to King's College Hospital, south London, in 2021. She had injured her pancreas while cycling after slipping on to the handlebars of her bike.
She died after developing an infection that led to sepsis - though an inquest found she could have survived with better care.
The hospital has apologised for its mistakes.
Responding to the news 143 NHS hospitals will be operating the scheme by 2025, Ms Mills said: "It shows an openness to the idea from hospital trusts, from doctors and nurses."
"Above anything, I think it shows that the need for it is widely recognised," she said.
The NHS is now working with Martha's parents to develop material that will advertise and explain the initiative in hospitals across the country.
Posters and leaflets will be available in cubicles, ward corridors and hospital kitchens, Ms Mills said.
"We want people… to feel empowered to use it, and not feel they might offend somebody by using it," she said.
The infected blood scandal was another example of "preventable harm" within the NHS, Ms Mills said.
More than 30,000 people in the UK were infected with HIV and hepatitis C after being given contaminated blood products in the 1970s and 1980s.
Professor Sir Stephen Powis, national medical director of NHS England, said the rule change will "represent one of the most important changes to patient care in recent years".
The initiative will allow "staff, patients and families to immediately raise concerns and bring about an escalation in care in an easily recognisable and fast way", he said.