Beyonc Knowles and Jay-Z sent their friends blue Christmas presents thought to be in honour of their first child.

The superstar couple welcomed their daughter Blue Ivy Carter into the world on Saturday. There has been intense speculation about how the pair came up with the name, and it's now been suggested they settled on it several weeks ago.

"This baby is also being surrounded by touches of blue. This was the case over the holidays, when, in anticipation of the baby's birth, the parents-to-be sent pals blue Christmas gifts," People magazine reports it was told by a source.

Blue has particular significant for Jay-Z, who has three album titles featuring the word The Blueprint, The Blueprint 2: The Gift & The Curse and The Blueprint 3.

"I'm the Blueprint, I'm like the map for 'em," he raps in A Star Is Born.

In Go Crazy, he is heard spitting: "My favourite hue is Jay-Z blue."

Ivy is thought to be in reference to the number four, which is IV in Roman numerals. The digit is significant for both stars as Beyonc was born on September 4, while Jay-Z's birthday is December 4.

They wed on April 4 2008 and both have IV etched on their ring fingers in honour of that special day.

Fans of the celebrity couple are convinced these are the reasons they chose their daughter's name, with many taking to Twitter to discuss it.

"There's a meaning in Ivy Blue. IVy = a roman numeral for 4 which is Beyonc's favorite number and BLUE for Jay-Z's Blueprint albums. Wow (sic)," @omgitsralph wrote.