Stuffed toys may have caused baby's death, says coroner

A meth pipe was found on top of a baby steriliser at house the day the baby was found. Photo / 123RF

Numerous toys and blankets placed in a Sydney baby's cot by her drug-addict mother may have tragically led to her death, a doctor has told a NSW coroner.

An inquest is examining the sudden deaths of two half-sisters, known as BLGN and DG, who were three months and 19 days old respectively, in 2014 and 2015.

Police found an ice (methamphetamine) pipe on top of a baby steriliser at the house the day BLGN was discovered unmoving in her cot, which was filled with many soft toys, blankets, an adult-sized pillow and two baby bottles.

Forensic pathologist Professor Roger Byard said the crowded cot posed a "potentially dangerous sleeping environment" that may have led to accidental suffocation.

"If those (items) were over the nose and the mouth, it's quite possible that BLGN could not breathe properly," he told Glebe Coroners Court on Thursday.

The court previously heard the mother told detectives she discovered her baby's face covered by a blue blanket, but on Monday she said she could still see her child's nose, mouth, eyes and a small part of her ear.

Prof Byard couldn't determine a time of death but assured family members in the courtroom that if she had died of sudden infant death syndrome, the process would have been very quick and painless.

"It's usually in their sleep and they just don't wake up," he said.

Prof Byard said he struggles to educate the public about safe infant sleeping habits.

"You have got to be so careful. We used to call SIDS cot death," he said.

"Young people who have drug habits ... it's very hard to get the message through."

On Wednesday, the family's drug dealer flatly denied allegations from his ex-mistress that he killed BLGN the night before she was found unmoving in her cot.

Prof Byard noted that in the event of deliberate suffocation from a hand or pillow, he wouldn't expect to find any evidence on the child's body.

He listed the cause of death for both girls as "undetermined".