The former All Black, Highlanders, and Otago rugby player visited Dunedin yesterday, before the trust's Otago launch on Tuesday.
The trust has been formed to support parents of sick and premature babies.
It would also pay for equipment and education for nurses.
Mr Kronfeld's son Cassius spent nine days in a neonatal intensive care unit in Auckland after he was born by emergency Caesarean section in September.
Cassius was suffering complications arising from meconium aspiration, when the baby consumes fecal matter in the womb; his vital organs had been deprived of oxygen and he had to "fight for his life" for a few days.
"For me, as a male, all my life I have been able to do anything ... In this situation I could do nothing other than be there," Mr Kronfeld said.
Sick babies knew the sound of their parents' voices; his baby son's brain monitor, which would flat-line, went "all over the place" upon hearing him or partner Bronwyn Illingworth (38) speak.
It was crucial at least one parent was able to be in hospital with their baby without worrying about work or money.
"You can't put a [dollar] figure on how much good it does that child."
Mr Kronfeld said his family was lucky to have the financial resources to make that possible.
He hoped the trust would help other families for whom money or work might stand in the way.
Now based in Auckland, and his son's main carer, Mr Kronfeld said his 6-month-old was now a "happy little dude", who hardly cried and loved meeting people.
Otago Neonatal Trust chairwoman Debbie Sinclair said there was "nothing" for parents when her son, Andrew, was born premature nearly five years ago.
Mrs Sinclair was delighted Andrew got to meet Mr Kronfeld, at Dunedin Hospital's Newborn Intensive Care Unit, as it was his dream to be an All Black.
Andrew had ongoing respiratory health problems, although they were improving as he got older.
