"She was defenceless." What we know about the Sydney toddler kept on a strict 'vegan' diet.

— With AAP.

A baby girl was so neglected by her parents that when she was 19 months old she looked like she was just three months old, a Sydney court has heard.

The toddler’s parents – who can’t be named for legal reasons – have pleaded guilty to failing to provide for their daughter and causing serious injury.

They faced a sentence hearing at Downing Centre District Court on Thursday.

The girl, who was taken to hospital after she suffered a seizure in March 2018, was fed a strict diet by her parents which left her malnourished and suffering from rickets, a preventable bone disease. The court heard that the diet, which is believed to be vegan-based, was “severely lacking in nutrients for her to thrive”.

Her height and weight were also found to be markedly low for her age.

In a victim impact statement read to the court, the toddler’s former foster carer said when she first met the little girl she could not sit up, speak, roll over or hold her own bottle – despite being almost two years old. She weighed just 4.89kg and had no teeth when she was placed into care in August 2018.

The girl, who is now almost three, continues to stand out as different because of her parents’ crime to which she was “defenceless”, the carer said.

“When she meets new people socially they always ask her age and are shocked how small she is,” they said.

“This crime has had a long-term impact on her development.”

The pre-schooler, now almost three, is currently technically obese because her height – that of a one-year-old – is so disproportionate to her weight.

“It’s like her body is storing calories in case she needs them in the future,” the carer said.

After leaving hospital, the little girl had to attend an appointment every single day with a medical professional. She also needed to have her blood tested at least once a month.

“As she gets older she is becoming more traumatised by (the blood tests),” the carer said.

“She now begins to scream.”

The mother and father from Sydney’s eastern suburbs first faced court in May last year, after their child suffered a seizure.

After her seizure, the toddler was forced to spend a month in hospital, as she was suffering from rickets and malnourishment. She was also acutely deficient of vitamin D, vitamin B12, zinc and iron.

Within just six months out of the care of her parents, the young girl was finally able to stand on her own and crawl.

According to court documents, the toddler’s mother told doctors that her daughter would eat a cup of oats with rice milk and half a banana for breakfast as well as a piece of toast for lunch.

She would often eat oats again for dinner.

It was also found that the girl had no birth certificate, no follow-ups at hospital after she was born and no immunisations on record.

The toddler also has two older brothers, who were on similar diets. All three children are currently in government care.