An Olympic weightlifter, who was not aware she was pregnant, has given birth while practicing for an upcoming competition.

Chilean Elizabeth Poblete, 22, who competed at the 2008 Beijing Games, initally felt 'unwell' while hoisting weights and called for a doctor. Soon after she gave birth to a baby boy whom she has since named Eric Jose, reported the UK's Daily Telegraph.

A trainer at Poblete's gym, Horatio Reis, was flabbergasted at the sudden birth.

"It was a surprise for me. A week ago I acted as a judge in a competition in Chile and this girl was competing.

"All went well and she won the competition.

"I could see she was a big girl, round and strong. That's all I noticed."

The boy was born six months into the pregnancy and remains in critical condition. It weighed just 2.25 pounds and measured only 15 inches at birth.