An inquiry into the convictions of serial baby killer Kathleen Megan Folbigg should focus on medical advances and new research, including on multiple "natural" infant deaths in the one family, lawyers have agreed.
Folbigg was jailed in May 2003 for at least 25 years after she was found guilty of killing her four babies in the decade from 1989, but the NSW government in August agreed to a judicial review of her case.
The 51-year-old's children - Caleb, Patrick, Sarah and Laura - all died aged between 19 days and 19 months.
She was imprisoned for three counts of murder and one count each of manslaughter and maliciously inflicting grievous bodily harm.
At a directions hearing in Sydney on Thursday, counsel assisting Gail Furness SC said the crown case at trial was "circumstantial" and consisted of four areas of evidence: the circumstances of each child's death, coincidence evidence, medical evidence and Folbigg's own diaries.
The crown case was that the "totality of the evidence" pointed to Folbigg's involvement in all four deaths, she said.
Lawyers for Folbigg lodged a petition in 2015 casting doubt on some of the evidence that led to her conviction.
Ms Furness said the main report relied upon in the application is an undated, 91-page paper by forensic medicine Professor Stephen Cordner from Monash University.
"He concluded that there is nothing from a forensic pathology viewpoint to suggest that any of the children had been killed," she said.
"He opined that there are identifiable, natural causes of death for two of the children, Patrick and Laura, and natural causes are a plausible explanation for the other two deaths, Caleb and Sarah, and the acute or apparent life-threatening event concerning Patrick."
She also highlighted a 2015 report from a mathematics professor which concluded "the jury was almost certainly misled" by expert statements "regarding the rarity of multiple SIDS (sudden infant death syndrome)".
Ms Furness said the inquiry should focus on medical opinions and evidence such as "new research or literature concerning incidents of reported deaths of three or more infants in the same family attributed to unidentified natural causes".
This medical focus was unopposed by Folbigg's barrister, Dr Robert Cavanagh.
According to former NSW District Court chief judge Reginald Blanch, who is heading the inquiry, hearings are unlikely to begin until late February 2019.
The location is yet to be confirmed but the inquiry is slated to run for six to 12 months.
