The two women, neither of whom can be named for legal reasons, have each pleaded guilty to a charge of failing to provide for a child causing danger of serious injury.

Documents tendered to Wollongong Local Court on Wednesday say the boy had had a complicated medical history leading up to the October 18 discovery, including cases of fractures bones and insomnia, an ADHD diagnosis, developmental concerns and a viral-induced wheeze.

Medical records revealed his mums had taken him to their GP 35 times in 12 months and made a further 31 hospital visits.

During those visits, the boy was found to be lethargic and had reduced levels of consciousness. Doctors initially suspected he was suffering from inflammation on the brain but were unable to make a formal diagnosis. On each occasion he was discharged after his condition improved.

Court documents said the boy's birth mother took him to hospital on the evening of October 10 with the same symptoms but they were discharged after a few hours with orders to return the following morning to the paediatric outpatient clinic.

The boy's condition was worsened overnight and he was unable to hold his own head up, bear weight independently or speak without slurring his words when he returned to the clinic.

Both the boy's mothers denied he had access to any medications in the house beyond simple painkillers.

However doctors decided to carry out a toxicology test, which revealed the boy had the prescription-only sedative benzodiazepine in his system - a drug designed to slow down the workings of the brain and the central nervous system.

When informed of the results, both the women could provide no explanation for the positive drug test.

However, one admitted she'd received a packet of Temazepam (a drug containing benzodiazepine) in the mail a few months earlier which had been left on the kitchen bench before being "put somewhere high".

Child abuse squad detectives were alerted to the case and a subsequent search of the women's house revealed an empty blister pack of Temazepam on the kitchen bench, along with various painkillers in the house.

The home was also in a "messy state", with piles of rubbish, cigarette butts and mouldy food scraps littered throughout the house, including close to the boy's cot.

Family and Community Services removed the child from the women's care and he remained in hospital for three days, during which time he returned to normal functioning.

A toxicology report revealed the boy had a cocktail of drugs in his system at the time including Temazepam (sedative), Oxazepam (sedative), Nortriptyline (antidepressant), Amitriptyline (antidepressant) and Lignocaine (anesthetic).

How the boy came to ingest the drugs or how much was consumed is not know, police said.

Text messages sent between the two women on the day of the boy's last hospital admission saw them discussing the empty blister packet.

"I found the empty sachet which was a full sachet last time I knew," one wrote.

"Look, let's not tell them [authorities] yet and if there is something in his urine then we could explain 'well he must have gotten into it without us noticing'," the other responded.

Both women remain on bail and will be sentenced in Wollongong District Court at a later date.