Beyonce finally popped, giving birth to a baby girl named Ivy Blue Carter in New York City on Saturday

Proud dad Jay-Z, real name Shawn Carter, was at the hospital where Beyonce reportedly birthed Ivy by c-section — and shortly after her arrival … J & B’s famous friends started sending out birth announcements on the Internet.

Rihanna tweeted, “Welcome to the world princess Carter! Love Aunty Rih”

Hip-hop mogul Russell Simmons also took to Twitter, saying … “congrats to my good friends Beyonce and Jay-Z.”

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