All seven died in the state's North or North-West.

One infant and one child died as the result of a car accident; four infants died from Sudden Infant Death Syndrome as the result of inappropriate sleeping arrangements including co-sleeping with a parent and/or sibling; and one infant drowned in a bath after being left unattended by a parent.

The only link between the cases is the fact the infant and/or child were known to child safety services.

An expert, who has analysed the cases and prepared a report for Coroner Olivia McTaggart, gave evidence to the court on Monday.

A suppression order prohibits the naming of the witnesses and the families in this inquest.

The expert said what was common across the cases was that they involved young parents, fathers who were not engaged with child safety services, and the families were from rural or regional areas of social and economic disadvantage.

"These sorts of families are the bread and butter of the department," the expert said.

"The difficulty for the department is they are not given the [resources] to deal with this level of disadvantage."

In reference to one case, the expert described the actions of child safety services as "manifestly deficient".

In this case, an infant and its teen mother died as the result of a car accident.

The expert said the department's actions were problematic in terms of contact with the family and the assessment of risk, which the expert said failed to take into account considerable previous interactions between the mother, the father and the department in relation to ongoing incidents of domestic violence.

They said the department also failed to treat the young mother as a child herself.

"The service response was haphazard and patchy," they said.

"Active intervention by the department was required in a timely way."

The expert said the department's inaction could have contributed to the both deaths and that the infant and mother should have been removed to a place of safety.

In relation to one of the other cases, the expert said staff shortages resulting in increased workload at a department office was a factor.

"It did appear to hinder the timely action by the department," they said.

In this case, the infant drowned after being left unattended in the bath for a short period by a parent.

The expert said child safety notifications related to emotional neglect and supervisory neglect had not warranted the department removing the child from the home but staff should have conducted a more active investigation.

"Even with a more timely intervention and assessment, the prevention of the drowning incident could not be guaranteed," they said.

"The death was certainly tragic but it came out of the blue."

The expert said any decision to remove a child from their home needed to be considered carefully.

"The attachment of parents to infants is quite critical and there are significant impacts if that is disrupted," they said.

"It is justified in some circumstances."

The inquest continues.