Now 10 months old, he was one of 374 boys born last year to have been given the name.
"Years ago, it was a very popular boy's name," Mr Newton said.
"I was very surprised when I saw the list."
Jack's elder brother, Oliver, now 12, has the second-most popular name in 2012.
Mr and Mrs Newton have the name Jack in their family histories, but Mr Newton said it was personal preference that made his choice.
"It's quite a strong name," Mr Newton said.
"There's Jack Nicklaus the golfer, but I'd always liked the name.
"My father's John and Jack is also short for John."
Mrs Newton said if the baby had been a girl, she was worried that so many strong girls' names had already been taken by her large extended family.
"You can't have the same name as your cousin."
With a boy on the way, however, there were more options available and Mrs Newton was happy to leave naming rights to Dad.
Jack himself has a taste for the tried and true, with his favourite toy being a 20-year-old bus that had belonged to one of his older cousins.
Mr Newton is an accounts manager for Cable Price and runs the lower North Island contract for Isuzu.
Jack has also finally got the hang of a full night's sleep, much to the relief of his parents. Mr Newton says: "It took 10 months but he got there."
Nation's top 10
Top 10 Boys' Names for 2012 (2011 place in brackets):
Jack (10)
Oliver (3)
William (5)
Liam (1)
Mason (15)
Samuel (7)
Jacob (11)
Lucas (4)
Ethan (16)
Noah (6)
Top 10 Girls' Names for 2012 (2011 place in brackets):
Olivia (2)
Sophie (3)
Emily (9)
Charlotte (5)
Ruby (1)
Isabella (4)
Ella (7)
Amelia (10)
Sophia (15)
Ava (12)
