Beyonce and Jay-Z welcomed baby girl Blue Ivy Carter into the world late Saturday evening in a private wing of Lenox Hill Hospital, numerous media outlets reported Sunday.

Music mogul Russell Simmons confirmed the arrival of the baby,  tweeting “congrats to my good friends Beyonce and Jay-Z,” according to the New York Daily News, which also reported that Gwyneth Paltrow, a good friend of the couple, also tweeted, "Welcome to the world Blue! We love you already."

Beyoncé had checked into the upper East Side hospital Friday night under the name “Ingrid Jackson,” a hospital staffer told the Daily News.

The couple rented out the upper East Side hospital’s entire fourth floor for $1.3 million, the Daily News reported.

Beyonce famously announced her pregnancy on stage at the MTV Video Music Awards back in August.