A woman gave birth to a 10 pound baby girl less than one hour after discovering she was pregnant.

Katie Kropas, 23, from Weymouth, Massachusetts, was admitted to hospital for an ultrasound on Tuesday, after complaining of severe stomach cramps and back pain, only to be told by doctors that she was actually nine months pregnant and ready to give birth at any minute.

'I ended up having an ultrasound and with that they were like, "You're full term and giving birth now", she told local news channel NECN.

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A sweet surprise: Katie Kropas, 23, was told that she was expecting a baby just one hour before giving birth

New mother: The catering supervisor welcomed her 10-pound baby girl Ellen Olivia on Tuesday

Baby weight: Katie, from Weymouth, Massachusetts, thought that she had put on a few pounds over Christmas and had no idea that the extra weight was actually an indication she was pregnant

'I found out at 10.15, I had the baby at 11.06.'

The new mother admits she 'doesn't know' how the pregnancy went unnoticed - but insists she was using birth control right up until her daughter, Ellen Olivia, was born and had even been having regular monthly cycles.

Although she confessed she had put on some weight and noticed her feet had become swollen, she put it was down to a combination of over-indulgence during the holiday period and too many hours spent on her feet while working as a catering supervisor.

'At the time, I was like this has got to be a joke but, I had no idea what to think,' she added.

'I don't know, I wish I had a better answer but I think that being on my feet all the time for work, and Christmas is so busy as it is, it just caught everything off guard.'

Mother and baby: Despite the surprise, the young mom is loving her new role

'I didn't know what to think': The news of the pregnancy was a complete surprise to Katie and her boyfriend

After discovering his girlfriend was expecting, Katie's long-term boyfriend rushed to get hold of her mother so that she could be there to support her daughter as she welcomed a child of her own.

'[He said to me]: "Katie's nine months pregnancy and we didn't know she was having a baby"' new grandmother Karen Kropas said.

'And I said ha ha ha, put Katie on the phone and he was like, "Karen, this is serious, how soon can you get here?"'

She added that, while she had heard stories similar to that of her daughter in the past, she had never really taken them seriously. After seeing it happen to her own child however, she urged others to recognize that 'it is real and true and it happens'.

'This is just the beginning': Despite the initial shock, Katie admitted that she and her boyfriend are 'having a lot of fun' being parents

'It happens': Katie's mother Karen said that she had never thought situations like this were possible, but having seen it with her own eyes, she is urging others to accept that surprise pregnancies 'are real'

Professional opinion: South Shore Hospital's Dr Kim Dever said that it is not uncommon for first time mothers to be unaware of what some might see as obvious signs that they are pregnant

Indeed, one of Katie's doctors at the South Shore Hospital in South Weymouth explained that first-time mothers often don't know what symptoms to look for in a pregnancy and can often miss what some people might consider to be the most obvious signs.

'They aren't perceiving those symptoms,' Dr Kim Dever said. 'Whereas when you're on the lookout for them, you're waiting for it to happen.'

The family are now preparing to settle three-day-old Ellen Olivia in at home - but first have to rush out and buy all of the essentials for their new daughter, from a crib to diapers.

And despite the initial shock at finding out about the surprise pregnancy, Katie and her long-term boyfriend are overwhelmed with joy at the new addition to their family.