This was accompanied by a "horrible" urge to vomit, but still, Ms O'Neill, then 36, thought she was okay.

"My first thought was maybe it was mastitis because I was still breastfeeding but then I thought it was indigestion because I was eating," she said.

Luckily her husband recognised the warning signs of a heart attack and took her straight to hospital.

Ms O'Neill was found to have a spontaneous coronary artery dissection (SCAD) and spent eight days in hospital before she was stabilised with medication.

She credits her husband with saving her life.

In Australia, SCAD is the leading cause of heart attack in women under the age of 50.

SCAD occurs when a sudden tear occurs within the layers of one or more arteries to the heart. This tear blocks blood flow which can lead to a heart attack and sometimes death.

Sarah Ford, President of SCAD Research Inc Australia, says women who experienced this condition are not the "typical picture" of heart disease.

"The average age of SCAD sufferers is just 42, 80 per cent of sufferers are women, and it typically occurs in healthy, often fit adults with no standard risk factors for heart disease," said Ms Ford.

For this reason, the organisation has teamed up with the Heart Foundation to raise greater awareness and remind "busy" young women not to ignore the symptoms of heart attack.

"Heart attacks are not always what you think. While chest pain is the most common symptom for men and women, women are more likely than men to experience the non-chest pain symptoms such as jaw and back pain, nausea and fatigue," said Julie Anne Mitchell, Heart Foundation National Spokesperson on Women's Health.

"If you experience these symptoms, you need to call triple zero immediately. The sooner you get to hospital the sooner treatment starts," she said.

Australian Associated Press