It’s official! Beyoncé gave birth to a baby girl Saturday night, according to EOnline!

30-year-old Beyoncé gave birth to Blue Ivy Carter at Lennox Hill Hospital in NYC. She checked into the hospital under the alias Ingrid Jackson.

THEIR BABY IS ALREADY ON TWITTER! READ MORE.

Rihanna tweeted to her new niece: “Welcome to the world princess Carter! Love Aunty Rih.”

Russell Simmons was among the first to celebrate the arrival, tweeting the new parents: “congrats to my good friends Beyonce and Jay-Z.”

Beyoncé told the world she was pregnant while onstage at the MTV Video Music Awards in August.

The couple married in April 2008 after dating for around six years.

THEIR BABY IS ALREADY ON TWITTER! READ MORE.