"My first instinct was that there must be some mistake," her mum Seona Donald said this week.
"We had one healthy daughter already and had no family history of any chronic condition ..."
But the signs were all there. There was no mistake.
Matilda was a "floppy baby" who always hated tummy time. She was unable to lift her head off the floor. She didn't bear any weight on her legs. She couldn't sit up unsupported.
She started rolling at 7 months but stopped at 10 months.
"Feeding herself was starting to become difficult," Donald said.
She said Matilda struggled to lift her arms off the high chair table to self-feed and putting her hands above her head when singing Twinkle, Twinkle, Little Star "was impossible".
"I spent a lot of those earlier days feeling numb and in shock, and many nights on Google and social media scrolling through the worst kinds of stories and images of people with the condition," Donald said.
Six days after Matilda was diagnosed with SMA, however, she started receiving the Spinraza treatment.
She initially qualified for the US drug company Biogen's extended access programme, which meant she could access Spinraza free of charge.
Now the drug is publicly funded in Australia, Matilda receives it through the Government's Pharmaceutical Benefits Scheme – again, free of charge.
Donald said after the second injection, Matilda started rolling again and just before her fourth injection, Twinkle, Twinkle, Little Star "was perfect".
To date, she has had 10 injections. She will have her 11th this month.
"To think where Matilda has come from in a little over two years and where she'll be when starting school in 2022 and then beyond, it is so exciting," Donald said.
She said her daughter is even taking unsupported steps now – "100 consecutive at last count".
"[Her] being able to walk and move in a way that nobody had expected has been completely amazing, life-changing, transformational. Our hopes about Matilda's future, and what she'll be able to do in the future have been completely transformed."
Meanwhile, here in New Zealand, Tama is still doing it tough.
He was diagnosed at 15 months old with SMA Type 2, so he doesn't qualify for Biogen's extended access programme, which is only available for SMA Type 1 patients under the age of 18 in New Zealand.
Yet the disease sometimes leaves Tama so weak he can't lift his head, or lift his hand to his mouth to eat.
A small cough can cause him to go downhill quickly, as it did in October when he ended up in Rotorua Hospital breathing through a machine.
Tama's mum, Lisa Geddes, believes if her son doesn't get the Spinraza treatment, he will continue to get worse until the disease eventually takes his life.
"In three short years, he's already deteriorated really fast."
Geddes said they travelled to Starship Hospital in Auckland this week for an MRI scan on Tama's spine. They will return to Starship for more appointments at the beginning of February.
This is situation normal for Tama, and his mum. There are good days and bad days.
"Tama has been okay, he has hay fever at the moment so sometimes when he sneezes it causes his head to fall forward," Geddes said this week.
She said Tama would "absolutely love" to go to school when the time comes.
"He loves being around lots of people."
But Geddes said it is "extremely scary" to think about that. It worries her, but she is determined to make it happen.
"There is just a lot that will have to be sorted out before then to make sure he will be okay and have the support at school that he will require."
In the meantime, they continue to wait for Pharmac to make a decision about Spinraza funding.
The agency started evaluating an application for Spinraza funding in August last year and the rare disorders subcommittee met in late September this year to consider more information provided by Biogen about the drug.
Pharmac operations director Lisa Williams said this week in a statement that having a fixed budget means Pharmac needs to make careful and considered funding choices in the interests of New Zealanders.
"We understand Spinal Muscular Atrophy (SMA) has a devastating effect on people and their families and are working hard to fund the best medicines we can based on evidence."
Williams said Pharmac received correspondence from New Zealanders in support of the funding application for Spinraza.
"This feedback, along with supplementary information from the supplier, was included with the funding application to the rare disorders subcommittee for consideration at its recent meeting ..."
She said: "We are currently finalising the record of the subcommittee's advice and expect to publish its recommendations to Pharmac within the next three weeks."
View from Australia
Seona Donald says it is "a complete tragedy" that New Zealand doesn't publicly fund Spinraza.
The Sydney mum said the drug was lifesaving, life-changing and "totally transformational for the sufferers of SMA and their families".
"No one should be denied a drug that is clearly having such a profound impact on the recipients, and their abilities," she said.
Julie Cini, chief executive of Spinal Muscular Atrophy Australia, said seeing firsthand the positive effect Spinraza has had on the entire under 18-year-old community, "never ceases to amaze me".
"Children that were almost certain to die from the disease are now flourishing and achieving many new milestones never before experienced," she said.
"It certainly is a debacle over there in New Zealand with the Government not funding the drug."
Cini said rare disease medications would never be a viable option to a government due to, at times, their high cost and low patient cohort, "but that doesn't mean that they don't deserve to be given a chance to have treatment".
"All of our families not receiving treatment have chosen not to access the drug privately – as even we agree that it is unattainable to the average family not only in Australia but all over the world. Why should someone have to sell their house and be put in financial hardship to receive life-changing medications?"
• A Givealittle page has been set up to help Tama Hubbard fight SMA.