Beyonce is at the centre of baby rumours after husband Jay Z hinted she was pregnant.

The rap superstar was on stage with Beyonce at one of their On The Run shows in Paris when he changed the lyrics of his song Beach Is Better, to suggest that his wife is expecting a sibling for their two-year-old daughter Blue Ivy.

Jay was supposed to sing the line "I replace it with another one" but reportedly switched it to "cause she pregnant with another one".

His words sent the rumour mill into a spin, but concert-goers said Beyonce didn't react when her hubby changed the lyrics, and the couple have yet to comment on the pregnancy story.

During the show, Jay, 44, also told the crowd that the French city meant a lot to the couple.

"We love Paris. It's special to us because we got engaged here and this is where baby Blue was conceived," he said.

Beyonce, 33, previously used the stage to announce she was expecting Blue, rubbing her baby bump after singing Love On Top at the VMAs in 2011.