Congratulations are in order for Dan and Honor Cater as they have announced baby number four is on its way.

The sporting greats took to their social media accounts to share the news.

"My family are everything to me ... my happiness and my greatest success. We couldn't be happier to announce we're expecting baby number 4," Dan wrote on his Instagram.

While Honor said she's excited to meet the new family member "we're so excited to meet our newest addition and what a lucky little one to have 3 adorable older brothers".

The Instagram announcement shows the family of five soon to be six together with Honor holding a number four balloon.

This will be the pair's fourth child.

The couple have three sons: Fox was born in 2015, Marco in 2013 and Rocco in 2019.

The Carters aren't the only sporting couple in New Zealand to add new additions to their families later this year.

Last month, Richie and Gemma McCaw announced they are expecting their second child.

The pair have a young daughter named Charlotte.

The Carters married in 2011.

The former All Blacks playmaker made his test debut for the national side in 2003.