A wife, mother and partner in a law firm, she was also 18 weeks' pregnant when she went to Holmesglen Private Hospital in Brighton with vomiting, diarrhoea, a fever and chills.

Five years to the day after her death from sepsis and multi-organ failure, the 37-year-old's father Brian Moylan has urged State Coroner John Cain to be courageous in pursuing facts around her death, and to make bold recommendations to improve Victoria's health system.

His daughter was determined, motivated and not afraid to speak up and so her death must be a catalyst for changes to the systems that failed her, the retired GP said.

"Annie made all the right choices. She responded with diligence and care for her unborn baby," he said.

"She trusted her attending doctors, and the hospital systems, yet she was given nothing to fight with until she was in organ failure."

After a lunch with colleagues Ms O'Brien began to feel unwell on August 14, 2017. Her obstetrician advised rest and paracetamol but after no improvement she headed to hospital.

Hui Li Shi was the sole doctor in the full 10-bed department that night and took an hour to see her.

With a temperature of 40.3C she was diagnosed with gastroenteritis and given fluids.

When her membranes spontaneously ruptured at 11.30pm Dr Shi thought it was the fever and gastro causing a miscarriage.

She told the Victorian Coroners Court on Monday that she hadn't considered sepsis.

"You have to make a clinical judgment. As a clinician, I made that judgment at the time unfortunately. I'm sorry."

With the benefit of hindsight, she should have thought whether something else was going on, Dr Shi said.

Ms O'Brien was transferred to St Vincent's Private Hospital where she delivered her baby girl stillborn at 2.12am on August 15.

Half an hour later, she was given her first dose of antibiotics - an hour after her obstetrician went to look up sepsis guidelines and 46 minutes after the prescription was written.

After surgery, plasma and platelets she went into cardiac arrest. She was resuscitated but continued to deteriorate.

It wasn't until about 12.30pm that family was told her condition wasn't survivable, Dr Moylan said.

"At no time were we advised that all of the close family members should be told to come in," he said.

Life support was turned off and Ms O'Brien died at 1.55pm. She had a 14-month-old son.

"The failure of effective regulation of private hospitals and private hospital EDs in Victoria was contributory in the circumstances that led to Annie's death," Dr Moylan said.

He said her family had been burdened with the task of investigating her death and frustrated in their search for answers.

"I challenge this court to be courageous and to be forensic in pursuit of the facts concerning Annie's death and to make bold findings and recommendations toward improvements in the health system in Victoria."

Participation in reviews by Safer Care Victoria is voluntary for private hospitals, but that changes from November.

SCV's patient safety review manager Megan Goadby said neither private hospital reported Annie's death but both provided some documents for an external review.

Australian Associated Press