Rather than waking her child, the mum popped in to the store by herself. She penned a note and put it on the baby's blanket. "My mum's in doing the shopping. Call her if I need anything," it read, followed by her mobile number.
Shortly afterwards the baby was spotted by a man and woman who had parked nearby. They were shocked, and decided they couldn't leave the baby there alone. They called the mum and waited with the baby until she returned.
"It's with the police now," the man told the Herald on Sunday. "I didn't want this to happen."
But it didn't end there. A photo of the baby was uploaded to Facebook, and so began a storm of moral fury that, through the power of social media, has spread around the globe.
What may have seemed like a line-call to a stressed mum has now been castigated in the New York Daily News, the International Business Times, the Sydney Morning Herald, Belgium's De Standaard and Britain's Daily Mail and many more media outlets.
Child welfare issues are guaranteed to raise the collective blood pressure - and it's no surprise, given New Zealand's appalling rate of child abuse, neglect and injury. Child Youth and Family received 152,800 notifications for the year ending June 2012. ACC statistics reveal that New Zealand children are twice as likely to die through injury or accidents than children in Australia, and three times as likely as English or Welsh children.
Such stats inform much of the debate on social media sites. But as passions flare, it seems a good time to ask ourselves pointed questions on our own parenting. While it's undeniable that leaving a baby in a car is not good, does the baby's mother really deserve to be vilified so publicly? Haven't many good New Zealand parents done silly things when stressed, busy or plain exhausted?
An unscientific internet poll conducted by Herald on Sunday revealed illuminating facts around "the baby in the car" drama. Of the 271 respondents, 82 (30 per cent) thought the mum in Porirua was probably stressed, lacking sleep or support and deserved empathy.
Sydney Watson posted: "I can't believe this is such a huge issue, it was probably the mistake of a very tired mother who popped into the store to get something important."
Another 95 (35 per cent) considered the mother's actions to be inexcusable, as summed up by Julia Searle. "Bad parenting! No one should leave a young child in a car unattended. It's a basic care and protection rule for our children!"
A further 28 (10 per cent) admitted to having left their child in the car for a few minutes when shopping. Teia Clarke says: "I'm a parent and I have left my baby in the car at the gas station, because you don't get service anymore. I locked the car and I could see it at all times, so I guess the 'sucky mother of the year' award goes to me!"
The law on leaving a child in the car is murky. It is illegal to leave a child under 14 alone for an unreasonable length of time. "But the police will act on a case by case basis," says police spokesman Ross Henderson.
CYF general manager of operations Marama Edwards says few cases of children left in cars are drawn to their attention.
"Babies and young children should not be left without adequate supervision. It is potentially dangerous and could put children in harm's way," she says.
It seems, however, that many of us leave our children in cars under certain circumstances. Veronica (not her real name) is a good example. She dotes on her only daughter, Sarah, and makes sure she is never in harm's way. "If I was only going to be five minutes I quite often left her in the car with my beautiful, big, black German shepherd dog on guard - I thought that was quite sensible, actually. Strapped in, air circulating, with windows open, safe! She wasn't a newborn, though."
She doesn't condone leaving a child in a car for longer than a few minutes. "And I wouldn't ever leave a young baby alone in case they vomited out of the blue as happens sometimes."
Mum-of-three Brigetta Taylor disagrees. Leaving a child alone in a car is never excusable, she says. "In 10 years, I have three children and not once have I ever done this. I have always planned my day; and if not possible to take baby/toddler with me, I have not ventured out. We are all they have until they are able to communicate with us and that is a few years away."
Whatever you think, there's no doubt even the most diligent parents can make silly mistakes. Katherine Granich, the editor of parenting magazine Littlies, can empathise with the Porirua mum's slip-up.
"I have a 7-year-old daughter and a 17-month-old son," she says. "I was working in another part of town this afternoon and I actually forgot to pick my son up from daycare. I was stressed, the traffic was terrible, and I had a momentary lapse. He was fine, of course, but it shows what stress can do to your brain."
She says the combination of sleep deprivation, plus lack of education and support, can be huge factors in parental mistakes.
"When you are in the deep end of parenting, especially when you have a new baby, self-care can go out the window. We all make mistakes. The best thing we can do is to offer mothers compassion and support, rather than judging them."
In response to a Herald on Sunday appeal on Facebook, many parents revealed lapses of judgment. Mary Bradly says when she had her first baby, "I forgot I had her and left her in the bank."
Sarah Sinclair drove from Wanaka to Queenstown in a rental car, only to realise the baby's car seat hadn't been buckled in.
Cherry Redd says she has buckled her babies into their capsules, but forgotten to put the seatbelt around the capsule.Do these lapses make us bad parents? John Cowan, from family support organisation The Parenting Place, thinks not.
"No parent is perfect," he says. "It's actually amazing how much you can get wrong, and still bring up happy, well-adjusted kids.
"People often say, 'I was allowed to do this or that when I was a child and nothing happened to me', but that is misleading. There was actually a far higher rate of injury to children 20 years ago than today.
"You should protect your child from obvious dangers, but it's also important not to be overprotective."
Whatever your take on the infant left alone in Porirua, most parents know how bad silly parenting mistakes can make you feel.
Granich says the Porirua woman needs to be offered compassion. "I would ask if I could help her and what she needs to make things a bit easier. I believe that we need to support each other and lift each other up, not make each other feel ashamed."
All parents know the disapproving stares of passers-by, judging them for carrying their baby wrong, for feeding them wrong, for telling off a crying child, for not telling off a crying child.
At Pak'n Save in Mt Albert, McKenzie says being a new mum is tough, juggling the expectations of others, differing advice from books and professionals - and your own judgment as a parent.
She's felt guilt. Against all the advice in the books, McKenzie has breastfed little Neve to sleep. Sure, it might have been risky. Short-term, McKenzie might have fallen asleep; long-term, Neve might have become clingy. She's proud as punch of her little girl. "It worked out well, I haven't broken her."
