As reported in the wee hours of the monting the singer, 30, gave birth to a baby girl in New York on Saturday, according to various outlets, including Good Morning America and her hometown paper, the Houston Chronicle, which reported that "baby and mom are doing just fine." GMA reports the superstar gave birth via C-section.

"Welcome to the world, Blue," Beyonce and Jay-Z's close friend Gwyneth Paltrow tweeted Sunday. "We love you already." The actress also answered a "confused" fan who asked if the infant's name is "Ivy Blue or Blue Ivy," saying, "It's Blue Ivy!'. Early reports were saying Ivy Blue.

According to GMA,the couple chose "Ivy" because of the significance of the number "4" or "IV," — Beyonce and Jay-Z were born on Sept. 4 and Dec. 4, respectively, were married on April 4, 2008, and Beyonce's latest album is entitled 4.)

Confirming the big news? None other than superstar pal Rihanna, who tweeted Saturday, "Welcome to the world princess Carter! Love Aunty Rih."

Fellow hip hop icon Russell Simmons also wrote: "Congrats to my good friends Beyonce and Jay-Z."

The 30-year-old singer first announced she and her hubby, 42, were expecting at MTV's Video Music Awards in August. During her incredible "Love on Top" performance, she exclaimed, "Feel the love that's growing inside of me," before ripping open her purple sequined blazer to reveal her baby bump.