South African 400m world record holder Wayde van Niekerk and wife Chesney are expecting their first child.

"Crazy excited to announce we are having a baby," Wayde said in an Instagram post on Monday.

The professional athlete, who will be defending his title at the Tokyo Olympics in August, said the couple would be revealing their baby's gender "soon." "Blessings keep coming our way," he went on to say.

The announcement was accompanied by a custom illustration by Cape Town design studio, Yay Abe.