A young mother has spoken of her fear that she could die at any moment due to a rare heart condition that should have killed her at the age of three. Betheny Coyne, from Wigan, Lancashire, was diagnosed with a rare heart defect before she was born - and was never expected to reach her fourth birthday. But she defied medical predictions and now, aged 24, she is mother to three healthy children. This is despite being warned that each pregnancy could have placed so much extra strain on her heart that she would die. Fearing her heart is like a 'ticking time bomb ', she is determined to make as many memories as possible with her family, and will be getting married in February next year. Betheny Coyne, 24 (pictured with daughters Haley, Harper and Grace), was diagnosed with a rare heart defect before she was born - and was never expected to reach her fourth birthday . Miss Coyne said: 'If I didn't have my children or my fiancé, Mark, I'd spend my life worrying I was going to die. 'I can't have any more surgery on my heart so it's a case of living with my heart defect and ensuring I do everything I want to in life while I can. 'I have defied doctors by getting this far - so we just take every day as it comes and try to take pictures of everything. 'I just want to make sure that the kids are happy and that we make lots of memories as a family as I know my condition makes me a ticking time bomb.' Miss Coyne was born with a heart condition known as coarctation of the aorta, which caused her need open heart surgery three times as a baby. The condition makes it difficult for the heart to pump blood around the body due to a narrowed aorta, the main artery that leaves the left side of the heart. The risk is that it may narrow further at any time, meaning the blood will stop going round the body properly, and in turn cause complete heart failure. Miss Coyne's parents were first told their daughter had a heart defect before she was born, but it was only later scans that revealed the true extent of the rare condition. Due to her uncertain life expectancy, Bethany wore a heart monitor to school and went for regular check-ups. She still has to go for an ultrasound scan every six months to check her heart health. Miss Coyne (with partner Mark) was born with born with a heart condition known as coarctation of the aorta, which caused her need open heart surgery three times as a baby. Doctors warned being pregnant could have placed a fatal amount of strain on her heart - but once again, she defied the odds . Fearing her heart is like a 'ticking time bomb ', she is determined to make as many memories as possible with her family, and will be getting married in February next year after getting engaged on holiday last year . She said: 'I worry every time I go for an appointment about what they are going to say, it's a constant uncertainty. 'Growing up with the condition was difficult because it felt so unfair that I was going into hospital all of the time for tests and check-ups while other children didn't have to. 'The possibility of dying at any moment didn't really affect me until I had children. 'You just get on with life when it's just you, but when you have kids you have more responsibility and something to live for. Miss Coyne was born with a heart condition known as coarctation of the aorta, which caused her need open heart surgery three times as a baby. The condition makes it difficult for the heart to pump blood around the body due to a narrowed aorta, the main artery that leaves the left side of the heart. The risk is that it may narrow further at any time, meaning the blood will stop going round the body properly, and in turn cause complete heart failure and death. 'Now I worry about it all the time, but knowing that we are taking lots of pictures and have the wedding to look forward to makes it easier. 'It was only when I was told I probably shouldn't have children that I realised how much I wanted to have them. I knew I'd regret it if I never became a mum.' She became pregnant with her first child, Haley, unexpectedly when she was 19 - and before she met her now fiancé, Mark. She had previously been warned by her heart specialist that having children would cause a massive strain on her heart. She said: 'I was really worried when I fell pregnant, but I tried to live as normal a life as possible and focused on the baby.' Thankfully, her heart condition is not genetic, so there was little chance of her passing it onto her children. Speakiing about giving birth to her daughter in 2009, she said: 'I was so relieved. When I gave birth it went so well - it was completely normal.' The following year, she met her fiancé Mark Brimble, 35, in a local bar . Aware of the seriousness of her condition, she told him about it early on in the relationship. Thankfully, her heart condition is not genetic, so there was little chance of her passing it onto her children . Miss Coyne said: 'I can't have any more surgery on my heart so it's a case of living with my defect and ensuring I do everything I want to in life while I can. She is pictured at Disneyland Paris . She said: 'When I told him, I actually offered to leave him because I could see how it might get difficult later on. 'He was so understanding, though, he's been great the whole time we've been together.' On February 20 2013, Miss Coyne gave birth to the couple's first child, Grace - and was induced four days early as a precaution for her heart condition. Mr Brimble then proposed last May while they were on holiday and baby Harper arrived in the December. Miss Coybe said: 'We don't want any more children - the main thing now is having a great time with the three we have. 'Before Harper was born we took the girls to Disneyland Paris for Haley's fourth birthday and we had the best time. However there are constant reminders of her condition. At times, breathing can be very difficult and there are days when she feels exhausted. She said: 'Mark is an amazing dad, so I would have no worries about the children if I died.' June Davidson, Senior Cardiac Nurse at the British Heart Foundation, said: 'Years of research has helped to dramatically improve survival rates for babies born with congenital heart defects from a position where very few babies survived to one where almost all do.' 'However, more research is needed to better understand the longer term consequences of living with congenital heart disease so we can further improve the quality of more people's lives.'
Betheny Coyne was diagnosed with the defect before she was born .
Was not expected to live past her fourth birthday - but has defied the odds .
Is now trying to make as many memories as possible for her children .