"[The] topic of debate outside our hotel is, 'Is Heidi having another baby?'" he told concertgoers. "Heidi and I are having another baby!"
"I mean, Heidi is doing all the work," he said.
Klum was sitting in the sixth row of the concert hall with her kids and cheered from the audience when her hubby began singing. The two have been married since 2005.
The good news is that Klum enjoys motherhood. The model and "Project Runway" host said being a mom is the "most amazing thing."
"For me, now I'm second. Before, I was always first," she told USmagazine.com.