Beyonce announces she's pregnant with twins on Instagram

Blue Ivy is about to become a big sister - twice.

Beyonce and her husband, Jay Z, announced Wednesday on Instagram that the superstar singer is pregnant with twins.

"We are incredibly grateful that our family will be growing by two," said a statement signed "The Carters." The news accompanied a photo of Beyonce showing a baby bump while wearing just a bra, underwear and a veil.

Their daughter, Blue Ivy, was born in 2012.