The woman collapsed about 30 minutes into her plea hearing in the County Court on Thursday, after she and her husband pleaded guilty to charges over the boy's death.

The boy died on August 1, 2012, several days after he cut his big toe on an open tin of cat food that had been discarded in the house and was piled among junk, food scraps and faeces that filled every room of the house, in Melbourne's north-western suburbs.

The boy's mother, 41, and father, 43, both pleaded guilty to two counts of reckless conduct endangering a person and one charge each of failing to register the birth of a child.

The names of the couple and their son remain suppressed so not to identify the couple's other son, who was eight at the time of his brother's death. That boy is now in foster care.

During her arraignment, the mother was asked for her occupation and replied: "Deadbeat."

Prosecutor Susan Borg told the court that for two years prior to the boy's death, the family home was filled with rubbish, rotten food, faeces, bottles and open cans of cat food, and that the "walls were covered in filth".

"For two years before [the boy died] the premises was one of squalor," Ms Borg said.

Soon after the woman, who had been crying since before the hearing began, collapsed in the dock.

Chief judge Michael Rozenes asked that the court be cleared while the woman was being attended to by security guards. She was then taken to hospital.

Once the hearing resumed the woman's lawyer, Greg Thomas, said his client needed to undergo a full psychiatric assessment before her plea hearing could continue.

Judge Rozenes said the hearing would be adjourned until October 22.

He said it was the "preferable course" for the woman and her husband to appear in court at the same time, and acknowledged the man was worried for his wife's health.

The couple had their bail extended to return to court in October.

Earlier, Ms Borg said the cause of the boy's death had not been determined, as the faeces in the house had posed a bacterial danger while the open cans of food had created a physical risk.

She said the boy's toe had nearly been severed when he stepped on the open can.

In documents previously tendered to Melbourne Magistrates Court, the woman discovered her son lying lifeless in his bedroom and rushed him to an ambulance station.

One paramedic said in a statement to police that the boy had grey, mottled skin when he was brought to them and that he had a filthy bandage wrapped around his foot.

Photographs of the family home, taken by police and also previously tendered to Melbourne Magistrates Court, show rooms filled with piles of junk and food waste, and mould and faeces splattered across walls and appliances.

According to court documents, the boy who died was born at home, was never immunised or enrolled in school or kindergarten and only really had contact with his immediate family members.

Neighbours told police the boy was quiet and withdrawn, had poor speech and always appeared dressed in clothing that was inappropriate for the weather.

The boy's death prompted an investigation by Bernie Geary, the principal commissioner of the Commission for Children and Young People, and details about the case were conveyed to the office of Community Services Minister Mary Wooldridge.

The State Coroner is also expected to investigate.