A midwife has today been accused of a "gross breach" of her duties over the home birth of a baby who died.

Neonatologist Philip Henschke told the Coroners Court there was a 20-minute delay from when the baby's heart rate dropped to a life-threatening 80 beats a minute before midwife Fiona Hallinan decided it was time to get the mother to hospital.

The family's home was a three-minute drive from the Monash Medical Centre.

Dr Henschke said there was nothing to justify Ms Hallinan's actions and her failure to warn the mother, Kate Thurgood, that her baby's heart rate had dropped dangerously low had "directly contributed" to the baby's clinical condition when he was rushed to hospital and found to have no pulse.

"The baby was profoundly comatose," Dr Henschke said.

Coroner Kim Parkinson is investigating the circumstances and cause of death of Joseph Thurgood-Gates in December 2010 and the actions of Ms Hallinan and another midwife, Jan Ireland.

Ms Hallinan has given evidence at the inquest saying she considered Ms Thurgood a high-risk case because she was more than a fortnight past her due date. She attended the birth because she was afraid her patient might otherwise attempt a "free birth" alone.

Ms Thurgood, 41 at the time of the birth, had emergency caesarean sections and gestational diabetes in her previous pregnancies but wanted a vaginal birth at home for her fourth child.

Ms Thurgood and husband Dwayne Gates had three children, including twins, who were all born by caesarean section before Kate discovered she was pregnant in March 2010.

On December 13, 2010, when Kate was 42 weeks pregnant, she attended Monash Medical Centre with what she described as a heavy bleed.

She was seen by obstetrician Dr Peter Neal and scans revealed both baby and placenta were fine except the baby was in a breech position.

Dr Neal suggested Kate have a caesarean, which she declined.

Due to the bleeding, Kate was admitted to hospital for two days and went home to Clayton on December 15.

She went into labour at 4pm the next day and Ms Hallinan arrived about two hours later.

Her labour intensified quickly around 8.30pm, so Ms Hallinan contacted a second midwife, Jan Ireland, to attend and assist.

Dr Henschke said Joseph's heart rate dropped to 80 beats per minute at 9.15pm but it wasn't until 9.35pm when Ms Hallinan said Kate had to go to hospital.

He said Ms Thurgood was repeatedly reassured by Ms Hallinan that Joseph and his heart rate were fine.

Asked about the need to not panic or alarm Ms Thurgood during the home birth, Dr Henschke said there had to be a point where the mother was told about the situation and given the opportunity to say: "What are we going to do about this?"

Joseph was born at 10.16pm but by the he time he was admitted to hospital, he was limp, not breathing and had no heartbeat.

He died on December 21 when his life support system was switched off.

The inquest continues.