When Erin Langmaid woke up to severe cramps, the 23-year-old model brushed it off as a severe bout of food poisoning.
Hours later, at 9pm, she asked her long-time partner Dan Carty to help her to the bathroom – and just 10 minutes later she gave birth.
When Dan opened the bathroom door, he found Erin slumped on the floor, shocked and frightened.
The new mum sat frozen as she stared at their precious but totally unexpected newborn baby girl.
"We had not one hint or clue I was pregnant," Erin, a full-time pharmacy assistant and part-time model, tells Woman's Day from the family's East Geelong home.
"I was on the floor, and I felt this need to push and she suddenly popped out.
It's all still very much a blur.
Dan called 000 because she wasn't responding, and we thought she was dead.
The emergency operator talked him through, and then we heard her little cry.
Our hearts melted.
Isla May Carty, born at 37 weeks and weighing a healthy 3.6kg and measuring 52cm in length, was rushed with her mum to a nearby hospital where Erin underwent emergency surgery.
"The umbilical cord was severed during the birth and I had haemorrhaged badly, so I was in theatre immediately," she says, adding that Isla got a clean bill of health despite her traumatic arrival.
According to medical experts, "surprise" pregnancies are more common than people think.
"They call it a cryptic pregnancy. I had no morning sickness, I hadn't gained weight, and I was wearing the same clothes. We had been holidaying in Bali two weeks before and I was in a bikini!" says Erin.
"I've always had an irregular cycle, along with severe cramping, so I didn't question it."
Dan, 31, recalls breaking the news to the two new sets of grandparents.
"For both our parents, it's their first grandchild! I said Erin is in the operating theatre and she's going to be OK, but you need to be here," he says.
"After the initial shock, they've become our biggest supporters. Now they find any excuse to drop in!"