Celebrity friends have taken to Twitter to congratulate Beyonce Knowles and Jay-Z on the birth of their daughter.
Gwyneth Paltrow and her husband, Coldplay frontman Chris Martin, are close friends with the new parents and Paltrow tweeted to say the baby would be called Blue Ivy Carter.
The subject was a trending topic on the social networking site on Sunday, but until Paltrow waded into the flurry of speculation it was thought the child was to be called Ivy Blue.
She tweeted: "Welcome to the world Blue! We love you already."
Rihanna also offered her congratulations to her friends, tweeting: "Welcome to the world princess Carter! Love Aunty Rih."
Cheryl Cole wrote: "Congratulations to Beyonce and Jay on the birth of their first child. Welcome to the world Blue Ivy!"
According to reports, Beyonce gave birth in a hospital in New York with her husband, whose real name is Shawn Carter, by her side.
The star's sister Solange Knowles also tweeted, saying simply: "The most beautiful girl in the world."
There has been no official confirmation from the couple, however.
Beyonce announced her pregnancy at the 2011 MTV Video Music Awards in August, cradling her bump on the red carpet before unveiling it on stage during her performance by opening her sparkly blazer.