A grieving family have issued a poignant plea after a mother-of-three died battling an undiagnosed heart condition just five weeks after giving birth.
Cathy MacGuinness, 40, was rushed to Royal Prince Alfred Hospital on Easter Sunday after she suffered a cardiac arrest at home.
She spent almost three weeks in an induced coma before she died surrounded by loved ones on Saturday night.
Ms MacGuinness is survived by her partner Sebastian and their three children - seven-year-old Zoe, three-year-old Rosie and newborn Goldie.
The tragedy has prompted her family to urge everyone, particularly busy mothers, to be vigilant about their health and not to ignore minor symptoms.
Ms MacGuinness was unaware that she had dilated cardiomyopathy, a condition that causes the heart to enlarge and struggle to pump blood effectively.
Her sisters-in-law, Gillian Binchy-MacGuinness and Alison Scotland, believe that she would still be alive today had she been diagnosed and put on the right medication.
'It's so easy to dismiss yourself or just be like, 'oh, I'm just tired'. Or, 'yeah, I've been on my feet all day, that's why my legs are swollen', and not to give it a second thought because as a mother, you put everybody else in front of yourself,' they told 7News.
Sydney mother-of-three Cathy MacGuinness (pictured) died from an undiagnosed heart condition just three months after her 40th birthday
Her partner Sebastian (pictured) will raise three little girls, including a newborn, on his own
'Don't dismiss even the smallest symptoms… go and see your GP.'
Symptoms of dilated cardiomyopathy include fatigue, shortness of breath during activity or while lying flat, and swelling in the legs, ankles or abdomen, as well as palpitations, dizziness, chest pain and reduced exercise capacity.
Ms MacGuinness was described as magic in human form, who lit up every room she walked into and tackled all of life's challenges head-on.
As she took her final breaths, her hospital room was decorated from floor to ceiling with art, photos, messages and origami from everyone who loved her.
'She had this rare and extraordinary ability to really see you - to look at you and make you feel truly known, exactly as you are,' Joanna Allen wrote on a GoFundMe.
'She accomplishes everything she sets her mind to, looks incredible doing it and still makes everyone else feel a million bucks at the end.'
While Ms MacGuinness had a successful corporate career with Microsoft, the Commonwealth Bank, and most recently, aerospace company Alauda, it was her family that she cherished the most.
'Seb and her girls were her entire world, her greatest love, her proudest achievement, her reason for everything,' Ms Allen continued.
Cathy suffered a cardiac arrest a fortnight after giving birth to her third daughter Goldie
Cathy would still be alive today had she been diagnosed with dilated cardiomyopathy
Her family now urge everyone to be vigilant about their health and not ignore minor symptoms
'And beyond that, her love stretched wide and deep - to her mum and dad, her brothers and sister and all of their families.
'She didn't just love them, she cherished every single moment with them. She felt like the luckiest woman alive to call them hers.'
Like many families, Ms MacGuinness and her partner did not have life insurance, believing they had their lives ahead of them.
'Seb is now facing the unimaginable - raising three daughters, one of them a newborn, while navigating grief and loss no person should ever have to face - all alone,' Ms Allen added.
'We're raising funds to help ease the immediate financial pressure on Seb.
'Your generosity will help provide them with stability and breathing space as they begin to navigate life without her - covering day-to-day living costs, childcare for their three daughters and ongoing support as Seb finds his feet as a solo parent.'
The fundraiser has raised more than $130,000 within three days of launching.