A TEENAGER  was stunned to discover she was eight months pregnant after losing weight and dropping from a size 10 to an 8.

Saffron Heffer had no idea she was expecting and only developed a "sudden" baby bump when medics turned her son in her womb.

It was only when the 18-year-old's own mum spotted a strange line on her tummy that the teenager took a pregnancy test, The Sun reported.

Despite being on the contraceptive pill, it turned out Ms Heffer was 37 weeks pregnant, and gave birth to her son Oscar just six weeks later.

The shop worker said she put her missed periods down to the pill, and dismissed her cravings for Cornettos, lettuce and strawberries, thinking it was just because they were on offer at her local shop.

After taking the test, an emergency midwife appointment confirmed baby Oscar was back-to-back in the womb, meaning Ms Heffer barely had a bump.

The midwife twisted him around, causing Saffron's stomach to "pop" into a giant baby bump.

Medics also told Ms Heffer her son's skinny "chicken" legs might be to blame for her non-existent bump.

"It was a surprise for everyone," Ms Heffer, from Clacton-on-Sea in the UK said.

"I personally didn't believe it was possible, to not know you're pregnant, until it happened to me.

"I was taking it (the pill) so I wouldn't get my periods and then, boom, had a baby."

Ms Heffer had just weeks to get her head around the impending arrival, before welcoming healthy baby Oscar, who weighed 3.6kg, on June 3.

The teenager, then 17 years old, had felt tired for months, but doctors put it down to anaemia and a vitamin D and B12 deficiency.

Over time she began to lose weight, dropping from a size 10 to an 8, she said.

"At one point I thought I was dying because I didn't know what was wrong with me," she said.

"I was so lethargic and sleepy. I didn't want to go out; I didn't want to see anybody.

"I lost weight, I didn't gain any at all. I was in size 10 jeans, and I was in size 8 jeans when I found out I was pregnant."

Throughout her pregnancy the fitness fanatic continued going to the gym and still had regular sun-bed sessions.

While doing sit-ups, the teenager said she noticed her tummy went into a "funny triangle shape".

But her mum and workout buddy, Melissa Heffer, 46, just laughed it off with her.

"It just didn't click," Ms Heffer said. "Even my mum said she didn't think for a moment that I could be pregnant.

"It was mum who realised I had a pigmentation line on my stomach.

"She told me she wanted me to do a test, just to rule it out."

The pair were shocked when the test was positive.

"I had no stomach; nothing whatsoever," she said.

"In the end I did get a bump - it was huge.

"I saw the midwife, she turned him around and then I just gained a balloon.

"I was still in my size 8 jeans, but it was massive."

After seeing the midwife, Ms Heffer said her bump grew by the day - and all of a sudden she could feel her unborn son wriggling and kicking.

She said: "It was so strange, from feeling nothing at all to feeling everything daily is just unreal.

"I was absolutely shocked. I thought my life had ended.

"I'm 18 now and I was only 17 when I found out. That's a lot to take in for an adult, let alone a 17-year-old."

The shock left Ms Heffer feeling depressed and uncertain of how she would cope.

For two weeks she felt overwhelmed with stress, not knowing how she should respond.

But, realising that she couldn't change what was happening, Ms Heffer said she faced her situation head-on, refusing to let the stress beat her.

"I was just like, 'Right, OK, I can do this,'" she said.

"I've been strong with other things before. This is a bit bigger, but I just got on with it.

"A few weeks later he was born.

"I wouldn't turn back now. He's beautiful.

"He's perfect - so content - and just sits and sleeps and cuddles. He's lovely.

"I'm loving being a mum. It's so rewarding. The main thing I love is just seeing him happy.

"When he smiles and laughs, that's when you know you're doing a good job."

This article originally appeared on The Sun and was reproduced with permission