But the heartless thieves - most likely joy-riders - must have had a crisis of conscience and dumped the car back outside the hospital around a week later.
It had been "thrashed" and was leaking oil, but all of the baby gear and car seats were still there.
Ms Weir, 27, told all of the generous companies and individuals who had offered help, that while she and Mr Thompson were so grateful, their help was no longer required.
"They all turned round and said, 'We don't care, take it anyway'," she said today.
"I was so overwhelmed with that. I'm gobsmacked."
Ms Weir had gone into labour about 8pm on February 13, but there were soon complications - the umbilical cord had wrapped around unborn Carter's neck.
After an emergency C-section, Carter came into the world, healthy and well.
Mr Thompson, 31, walked out of hospital the next morning, having endured the most stressful night of his life where he thought he would lose both his unborn son and beloved partner, and found the family car had been nicked.
He had been on his way to collect two-year-old Koen from preschool to see mum and meet his new sibling.
But after APNZ highlighted their plight, they were flooded with support by people and organisations equally disgusted and saddened by the heartless crime.
Christchurch dealership Stadium Cars gave them a Toyota Carib.
"I swear to God, they must have known the type of car I love," Ms Weir said from her home in Hornby.
"It's nice and sporty which I love. I was just blown away. Everything has just been so fantastic."
But it hasn't stopped there.
The young couple are planning to get married later in the year and they've had offers - all individually - of a photographer, a make-up artist, celebrant, half-price on a DJ, and possibly even help with a venue.
Plunket gave them a month's supply of free nappies.
One of Ms Weir's friends organised a fundraiser which raised more than $700.
"I've got a lot of thank-yous to do once things settle down with Carter. He's healthy and wanting to feed 24 hours a day," Ms Weir said.
"I want the world to know just how fabulous people are."