But Sophie Alridge was still slipping into her usual clothes even when she was eight months expecting - which might explain why she had no idea she was going to have a baby!
Sophie, 20, from Dover, Kent, was totally oblivious to the fact that she was expecting and carried on going to festivals and on nights out, admitting to ITV's Daybreak: "I did everything they say not to do."
So when she started to have back pain, the carer believed she was suffering from period pains.
But when the pains grew worse, she called out paramedics, who informed her she was in labour.
Within half an hour, she was in A&E where she gave birth to her son Thomas, weighing a healthy 5lbs 8ozs. There hadn't been enough time to check into the maternity ward.
"Even the nurses in the hospital were quite shocked. I had about 12 people around me clapping and cheering when he was born. I've got over the shock finally now, and I wouldn't change him for the world."
She added: "I know it might sound really stupid to some people but I had no clue I was pregnant. I didn't have any symptoms. I didn't get morning sickness. I stayed wearing my size 10 clothes.
"It was a big shock to everyone when I suddenly arrived home with a baby."
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