Dr Shirley Lyford Tonkin, a prominent paediatrician and founder of the Cot Death Association, died peacefully at her Auckland home on Wednesday.

She was an advocate for child safety and one of three researchers involved in the development of a foam insert for car seats which helped prevent babies from choking.

The foam insert helps keep the babies' heads upright in a natural position instead of slumping forward.

Margret Free, chief executive of Sids and Kids New Zealand, an organisation raising awareness about sudden infant death syndrome, said Dr Tonkin was the person responsible for renaming cot deaths as Sids.

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She said the amount of work Dr Tonkin put into the cause was "absolutely endless".

"She was an amazing woman, she loved babies and was great with parents too."

Dr Tonkin researched cot death for more than 30 years and in the 1990s gifted bassinets to Northland communities to combat the issue of bed sharing.

She also created the Moe Ora scheme which provides newborn infants with a self-contained sleeping cradle, she said.

Mrs Free, who set up SIDS and Kids in 1994, had worked closely with Dr Tonkin over the years to help educate parents about keeping babies safe while they slept.

"She was one of the most leading people in the world in regards to SIDS, she's internationally known for her research."

Mrs Free said she knew that Dr Tonkin wasn't well but was still shocked to learn of her death today.

"I did know that she wasn't well but, by crikey, she was still a bright person. Her brain was always active and she was so kind."

A funeral for Dr Tonkin, 94, will be held on Wednesday, at St Marks Anglican Church, Auckland.

Dr Tonkin is the mother of Heather Tonkin who had a child with Princess Anne's ex-husband, Captain Phillips, nearly 30 year ago and had a daughter, Felicity.

Captain Phillips met Heather Tonkin, an art teacher and model from Auckland, when she attended a riding clinic he held in New Zealand in 1983. The pair met again a year later and she became pregnant.

• For more information about Sids, people can call the 24-hour helpline 0800164455.