Jenner, who became a grandmother for the sixth time on November 10, said it has been a joy to watch her son Rob become a father.
"The baby is so fabulous. Rob is so nurturing, and he's such a care giver and such a sweet man. It's really been such a joy to watch him go through this," the 61-year-old star said.
Jenner said it was Dream's mother Blac Chyna's idea it was to take part in the mannequin challenge from the delivery room.
"It was Chyna and her girlfriends who said, 'Let's do this,' and I thought that was such a great distraction," she said.