At just two days old, Blue Ivy Carter became the youngest person ever to appear on a Billboard chart when Jay Z released "Glory," which chronicled the couple's pregnancy struggles and included "B.I.C." (as she's credited on the track) crying at the end.
Blue's middle name is thought to be a reference to her famous parents' fondness for the number four, with "Ivy" representing the numbers' Roman numerical form "IV." Both Bey and Jay have the number tattooed on their ring fingers, married on Apr. 4, 2008 and Beyoncé even titled her 2011 studio album Four.
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