Terri Irwin has given her son Robert a playful punch on the arm after he made a cheeky comment about his pregnant sister on breakfast television.

Speaking to Channel 7's Sunrise program on Wednesday morning, the famous mother and son duo updated viewers on Bindi's pregnancy.

"She's due next month, so it's that sweet spot where you really miss being able to see your shoes," Terri said.

Robert then added: "She's massive now!"

Terri and Robert Irwin on Channel 7's Sunrise.
Terri and Robert Irwin on Channel 7's Sunrise.

The comment caused Terri to give Robert a whack on the arm.

Bindi and her husband Chandler Powell have been regularly updating fans on the pregnancy and have confirmed their first child is a little girl.

Originally published as Robert Irwin's cheeky dig at pregnant Bindi