23-year-old Klara thought she had cramps. She was actually in the final stages of labour.

While there are many unexpected turns in life, pregnancy is something the vast majority of people plan for. From who we sleep with, to birth control, financial planning, career consideration and where you live, starting “the next chapter” is something we’ve all considered at some point in our life.

For some though, parenthood comes as a complete shock, with approximately one in every 450 women don’t know they are pregnant until the half way mark at 20 weeks.

Even more extreme are the women who had no knowledge of their pregnancy until they went into labour.

For 23-year-old Londoner Klara Dollan, who had been taking an oral contraceptive for a number of years when falling pregnant, her weight gain was minimal and could put down to comfort eating following a breakup. Skipping her period was a regular practice, so its absence was not notable.

“I’d put on a bit of weight in most places, but I have a photo of myself in a bodycon dress at seven months pregnant and you wouldn’t know it,” the law student told the Daily Mail. “The only thing I would say is I noticed the top half of my stomach was very hard when I touched it, about a month before the birth.”

Severe cramping at work lead Dollan to return home, where she then spent hours pacing, with heavy bleeding and screaming coming later. By the time a neighbour came to check on Dollan and an ambulance was called, and “extremely painful urge to push” had already begun.

“My neighbour was in the corridor and I was screaming: “It’s a baby, oh my God! It’s a baby.'”

Klara Dollan didn't know she was pregnant until she went into labour. Source: Facebook.

Just minutes later, Dollan was cradling her newborn. "I couldn't believe I had a baby in my hands. I was in complete and utter shock," she says.

When she phoned her mother - who Dollan still lives with - to let her know what had happened there was silence at the other end of the phone.

“How is that possible?" her mother asked. "I saw you this morning and you weren't pregnant.”

Kim Walsh with baby girl Shelby. Source: Facebook.

Then 38-year-old Sydney woman Kim Walsh learned that she was set to become a mum only two hours before her baby was born, after a visit to the doctor with, you guessed it, "stomach cramps."

Having spent 15 years being told she was unable to have children, Welsh was able to easily attribute whatever symptoms may have appeared to other things - the idea of being pregnant so painfully far from her realm of possibly.

Kate Hudson was in her third trimester of pregnancy and travelling throughout Europe when she learned she was pregnant. Source: Facebook.

In 2014, then 22-year-old Melbourne woman Kate Hudson was up to seven weeks into a European holiday when she began to suspect she may be pregnant. But when she met with an obstetrician she was faced with the shocking news that she was actually 33 weeks along.

Understandably shocked and terrified, the student made her way back to Australia to be with her boyfriend and plan for the future.

It was on the flight home that everything hit her, with Hudson saying, "I basically cried for the 22 hours.” It was also the first time she felt the baby kick.

Assuming that she would have have presented with symptoms at some point, Hudson explained, “any belly I had I thought was just a food baby from all the eating I’d done in Europe over two months. I wasn’t nauseous, no morning sickness, little weight gain…  All I had leading up to it was constipation, and I went from a C-cup to a D-cup.”

Hudson and her partner Aaron celebrating Hudson's first birthday. Source: Facebook.

Welsh woman Gaynor Rzepka was 25 when she went into the toilet with a stomach ache and came out with a baby.

Like Hudson and Dollan, she says she had little to no symptoms. Her periods were regular and she only gained around 6 kilos throughout her pregnancy, which she attributed to over-eating during the Christmas period.

Rzepka ran a marathon at five months pregnant and says she only felt physical discomfort once, while lugging bags of potatoes at work.

Gaynor with baby Olly. Source: Facebook.

According to recent research, the unknown pregnancy can be scarily more common than you might think, with some of those classic tell-tale signs absent and age and intelligence acting as no boundary to those who have experienced the phenomenon.

What did you think when you first saw your baby? Post continues after video...3:59]

It's happening to women from all ages, all countries and all social demographics.

While all of the women in these stories had healthy deliveries and now have happy babies in their families, recognising that one sign is sometimes all a woman gets is imperative.

Because for women making a decision about a pregnancy, time is ultimately of the essence. And all of these stories go to prove that no one's pregnancy is the same as the next persons.