Blue Ivy Carter! (At least that’s what Jay-Z is telling pals at this point—the couple’s reps have not immediately responded to calls seeking comment.)

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

Rihanna gave baby Blue a warm welcome, tweeting: “Welcome to the world princess Carter! Love Aunty Rih.”

There has been no official announcement but Beyoncé is reported to have given birth to a little girl named Ivy Blue Carter.

Baby Ivy is said to have been delivered by Caesarean section at Lenox Hill Hospital, New York, with Jay-Z, 42 – real name Shawn Carter – at his wife’s bedside.

Before Christmas, unconfirmed reports also suggested the couple’s first child was about to arrive, but these were proved false.