American athlete Trish Staine thought the severe back pain she was experiencing stemmed from intense training for a half-marathon.

It was on June 22, 2013 and she ran for about two hours in preparation for the Garry Bjorklund half-marathon. The back pain was so severe and she decided to go to hospital.

And to her surprise, it turned out that the “back pain” was actually labour pain. During the emergency room examination, Staine and her husband were stunned to learn that medical staff had detected a fetal heartbeat.

She was whisked to the delivery room and in what she said seemed like five minutes later, her bouncing baby girl was born.

Staine says she had no idea she was pregnant until the back pain hit and then the surprise birth.

The mother of three said she hadn’t gained any weight or felt fetal movement in the months before.