She was expecting her period, but her partner Dominic was so worried he called their local doctor, who came round to examine her.
Diagnosing her pains as symptoms of irritable bowel syndrome (IBS), the GP prescribed Charlotte, 31, some indigestion tablets and headed off.
But less than an hour later, while Dominic was out running, Charlotte got the shock of her life when she went to the toilet – and felt a sudden gush of water.
"Then an umbilical cord popped out, followed by two little feet!” Charlotte, a lawyer from London, recalls.
Unbeknown to Charlotte, who lived in Amsterdam at the time, she had been pregnant for months – and her baby was on the brink of death.
She says: "Having watched One Born Every Minute, I knew the cord coming out meant the baby was being starved of oxygen, and a breach delivery is harder.
"I just knew I had to push with everything I had to get the baby out if it was going to survive."
Charlotte recalls being "strangely calm" once she realised she was in labour.