File photo: When the size 8 noticed her slinky dresses were feeling a little tighter, she chalked it up to all the alcohol. Picture: Pixabay

London - Like most teenagers, Charlotte Thomson loved going out at weekends.

So when the size 8 noticed her slinky dresses were feeling a little tighter, she chalked it up to all the alcohol.

In truth, the 19-year-old was in the last few weeks of pregnancy – but had no way of telling, as her baby bump was hidden beneath her ribs.

The nursery nurse only discovered the truth when she took herself to hospital with painful cramps in the middle of the night.

Doctors told her she was in labour –and her daughter Molly was born just a few hours later.

READ: Shock as Miss Teen gives birth in bathroom

Thomson, from Newcastle upon Tyne, said: "My stomach was completely flat, and I’d been having regular periods so it was such a shock.

"I thought [the weight gain] was from going out all the time. I still managed to get into my clothes so I just ignored it." She had also had stomach aches – but thought they were simply period pains. The real cause emerged after she woke in agony at 2.30am in December 2015. Miss Thomson, now 21, called a taxi to Northumbria Specialist Emergency Care Hospital.

She said: "A doctor told me that they needed to chat to a midwife – I was shocked. She revealed that I was nine months’ pregnant and in labour.

"I panicked that I wasn’t prepared and hadn’t bought any baby clothes."

At 4.30am a nurse rang her parents, Lynne, 50, a cleaner, and Vincent, also 50, an engineer. "I was so worried about what they would say," Thomson said. "They were really supportive and excited about their first grandchild."