The sling fabric may have been too close to the baby's face but positional asphyxia was most likely, NSW coroner Derek Lee concluded.

"The evidence establishes that the position of Harvey's neck, with his chin on his chest, compromised his airway," the coroner said.

"Harvey's relatively low weight may have resulted in less muscle and head control resulting in a difficulty in maintaining a patent airway from the way that Harvey was positioned in the sling."

Lee cleared staff at the centre and the manufacturer, which had affixed a suffocation warning to the wrap and shipped the product with an instruction booklet.

The guidance warned users of "particular features relevant" to Harvey's case: the need to carry babies upright and having their chin off the parent's chest.

Witnesses said Harvey's entire body was inside the loosely fitted sling and it was unclear to some that the sling held a child.

After Harvey's death was declared dead at the clinic, his devastated mother collapsed.

She declined to be involved in the inquest, but there's no suggestion of criminality or breaching her duty of care.

Given the mother didn't give evidence, the coroner couldn't determine whether NSW Health's absence of a policy directive on slings in April 2019 had any bearing on Harvey's death.

NSW Health has since made "appropriate changes" to advice about the risks of baby slings, the coroner said.

Banning slings and soft fabric carriers was a "fraught" issue and beyond the inquest's scope, Lee said.

A 2015 French study of 19 infant deaths in soft adult-worn baby carriers and slings recommended they not be used before the child is four months old.

Whilst removing slings was probably the only way to be certain of eliminating risks, it may be impossible to implement without ostracising people with a disability or from cultures that rely on slings, the inquest was told.

Instead, the Central Coast Local Health District has educated parents with a mnemonic.

TICKS (Tight, In view, Close, Keep chin off chest and Supported) advises parents to ensure the baby is held tight and high; is in view of the parent at all times; is close enough to kiss; is in a position so their chin is off their chest and never curled; and that their back is well supported and in a natural position.