That blue the favourite colour of Jay-Z is was kinda obvious because of the albums; The Blueprint, The Blueprint II and The Blueprint III.
Ivy is inspired of the roman number 4 IV. After the labor Jay-Z made a song called ''Glory feat. B.I.C'' for the ones who don't know what B.I.C stands for, it stands for Blue Ivy Carter.
In the song he reveals some things of their personal life, like that Beyoncé had a miscarriage and that Blue Ivy Carter was conceived in Paris!
Listen to the song here!
''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
You, you, glory.''