A heartbroken mum has detailed the shattering moment she ran over her one-year-old son, in a warning to other parents how quickly life can change in the blink of an eye.

Kelly Hopton-Jones, a paediatric nurse practitioner, explained in an Instagram post that the day started out like any other. She was taking her three-year-old daughter Lily to get donuts before a dance performance.

Her husband Brian was staying home with their one-year-old Henry, and the family would meet later on. Brian helped Lily into the car and was waving goodbye between the car and Henry, who was in the garage.

“In a matter of seconds, our son was run over by our car. I was driving,” Kelly revealed.

The couple’s neighbours stepped in to look after Lily, while the parents rushed to the emergency department.

Henry’s x-rays and scans came back normal, however the toddler does have fractures to his pelvis.

“I can’t even let my brain fully go to how different this situation could be right now,” Kelly wrote.

“It’s so easy to start questioning everything. If the morning had looked different. If Brian had gone to work like he normally would have, both kids would have been safely in their car seats.

“Why weren’t we holding him. Why didn’t I double check before pulling out. We could drive ourselves crazy with the what ifs, and honestly, we are a little bit. But accidents happen.”

The influencer says while they are in shock, they are incredibly grateful, but is using the accident as a lesson.

She says the family has new rules, including holding hands with her children around vehicles and not to assume they are where you last saw them.

“Even when you are not distracted. Even when you are not rushing. It can still happen in the blink of an eye.

“Accidents happen, and the only mistakes are the ones we don’t learn from. We’re on the lucky side of a very tragic accident.”