Jay-Z Beyonce Had Miscarriage Before Blue Ivy

1/9/2012 11:45 AM PST

Jay-Z just revealed ... Beyonce suffered a miscarriage before conceiving their daughter Blue Ivy.

The rapper dropped the bombshell in his newest song "Glory" -- which he released today in honor of Blue Ivy's birth this weekend -- rapping, "Last time the miscarriage was so tragic/We was afraid you'd disappear/But nah baby you magic."

The song was produced by Pharrell -- and even includes an audio sample of Blue Ivy crying just moments after she was born.

Among the proud fatherly lyrics -- "The most amazing feeling I feel, words can’t describe what I’m feeling for real / Baby, I paint the sky blue, my greatest creation was you."