Every time we feature a surprise birth story, we always end up asking ourselves: "But how could she not have known."
In this case, it's the story of 43-year-old Teresa Howard.
She knew all about what it feels like to be pregnant after having two sons, aged six and four.
So when she suffered stomach cramps on Saturday you'd think she'd have had an inkling that there was more amiss? Not a bit of it.
Even as she was being rushed to hospital, Teresa, had no idea she was expecting – but gave birth to a baby boy two hours later.
Teresa, from Mile Cross, Norwich, said: "I couldn't believe it!"
The drama unfolded after she begged her partner, Glen Toher, 42, to take her to hospital when her stomach ache became too painful to bear.
Glen said: "Teresa phoned me at work because her stomach had swelled up.
"She said she was so doubled over in pain she needed to get checked out for this wheat intolerance that her sister has."
The receptionist at Norfolk and Norwich University Hospital's A&E department immediately asked Teresa if she was pregnant.
"We both said 'no'," said Glen. "But then the doctor came and said Teresa was pregnant, congratulated us and said her contractions were five minutes apart.
"Not only had we just been told that Teresa was pregnant but that she was in labour too."
The baby's heart rate then dramatically started to drop. So Teresa was rushed for an emergency Caesarean section, but doctors then had to change their plans because she had started to give birth naturally and the couple welcomed their third son, Ethan, weighing 7lb.
Teresa admitted: "At first I was frightened about not bonding with the baby because I hadn't had the pregnancy to prepare.
"But as soon as they put the baby into your arms, you bond immediately.
"I just kept thinking, 'How did he survive in there for all that time without me knowing?'"
How indeed!
Teresa said she was even doing 100 abdominal crunches a night before Christmas in a bid to get rid of the 'muffin top' she said she had developed in the summer.
She said: "I thought the weight was due to me not eating properly, pigging out and not exercising - but I was still doing my size 12 trousers up."
She said she thought there would be people who do not believe her story because she was always cynical about similar tales herself.
She added: "I am the first person who sees these stories in the papers and on the television and says, 'Of course you know when you are pregnant'.
"I have had two boys - I felt rough almost all the way through pregnancy with both of them.
"I had heartburn, sickness, couldn't eat properly and I was huge.
"But now I am sat here eating humble pie because it has happened to me."