Singer Beyonce Knowles has given birth to a baby daughter.
According to contactmusic.com, the 30-year-old delivered the girl, named Ivy Blue Carter, in Lenox Hill hospital here Saturday night via a scheduled Caesarean section.
She's the first child of Beyonce and rapper husband Jay Z, who got married in April 2008.
Rihanna was among the first to congratulate through micro-blogging site Twitter:
"Welcome to the world princess Carter! Love Aunty Rih."
Hip-hop mogul Russell Simmons also tweeted, "Congrats to my good friends Beyonce and Jay Z."