01/08/2012 at 02:35 PM EST
and Jay-Z are now Mom and Dad!
The singer, whose pregnancy was closely watched and the subject of various rumors, gave birth to a baby girl in New York on Saturday, according to her hometown paper
. Mom and baby are doing fine, the Houston Chronicle
Sources tell E! News the little girl's name is Blue Ivy Carter
Apparently, she's a looker. "The most beautiful girl in the world," Beyoncé's sister, Solange Knowles, Tweeted Sunday morning
Friends of the superstar couple also used Twitter to offer public messages of congratulations:
"Welcome to the world princess Carter!" Rihanna Tweeted Saturday night
. "Love Aunty Rih."
"Welcome to the world Blue!" Gwyneth Paltrow
wrote on her Twitter page
Sunday morning. "We love you already."
Russell Simmons also acknowledged the new parents on Twitter: "congrats to my good friends Beyonce and Jay-Z," he said
Beyoncé, 30, checked into Lenox Hill Hospital on New York's Upper East Side on Friday, more than a month before her previously stated due date in February
On Thursday, the singer was photographed out in the city
covering her baby bump with a black blazer and a flowing scarf.
that the singer had given birth to a baby girl over New Year's weekend, Jay-Z and an "enormously pregnant" Beyoncé were spotted enjoying a dinner on Dec. 31
at Buttermilk Channel in Brooklyn, N.Y.
The first-time mom announced she was expecting
at the MTV Video Music Awards in August.
Reps for the couple did not respond to requests for comment.