Heidi shares four children with her ex-husband Seal - daughters Lou, 9, and Leni, 14, and sons Johan, 12, and Henry, 13.
Klum’s happy news comes three months after she shut down engagement rumours after she was spotted wearing a huge diamond ring on her left finger at the Emmy Awards.
“I don’t know why everyone keeps saying that. Everyone is asking me. When you do what I do, you wear a lot of fashion. A lot of jewellery. I always look for something that goes with the outfit. So, I wear big rings,” the America’s Got Talent judge told PEOPLE in September.
Klum also said, “there is nothing more to it than that,” though she called Kaulitz “absolutely wonderful.”