The couple are also parents to their daughter Kobe - and two Siberian Huskeys Kota and Kylo.
Many in the New Zealand rugby community, including All Black TJ Perenara who also recently welcomed a child, congratulated Savea on the news on Instagram.
Savea will miss out on the All Blacks' third Bledisloe Cup test on Saturday against the Wallabies in Sydney to be with his family.
The No 8 has started both of the All Blacks' tests this year at the back of the scrum, alongside Sam Cane and Shannon Frizell - opening up a spot for a debut start for Blues rising star Hoskins Sotutu to take over the reigns this weekend.
The All Blacks take on the Wallabies at ANZ Stadium in Sydney at 9.45pm on Saturday.