Many believed the tot's middle name was in reference to Beckham's jersey number when he played for Manchester United and England, as well as the hour and month of her birth and her weight.
But David Beckham has elaborated on the couple's reasons for the unusual pick - and he's adamant 'Seven' has more meaning than has been speculated.
In a video clip posted on his Facebook.com page, Beckham says, "A lot of people have assumed that it's just because it was my shirt number that I wore for many years, and part of it is. Part of it is because I had so much luck around wearing that number, wearing it for England, wearing it for Manchester United - it was such an influential number throughout my career, and a lucky number, but that wasn't the main reason.
"The other reasons behind 'Seven' were because it symbolises spiritual perfection, Seven Wonders of the World, seven colours of the rainbow and in many cultures around the world, it's regarded as a lucky number. We love the name. We love Harper Seven."
And he reveals Harper, "an old English name", came about because Victoria has always been a fan of author Harper Lee, who wrote her favourite book To Kill A Mockingbird.
He adds, "We're very proud of having her in our lives and our family. It's an amazing time for our family right now."
Little Harper has three big brothers - Brooklyn, 12, Romeo, eight, and six-year-old Cruz.