Heidi Klum hiding baby bump?

Heidi Klum Seal

, are expecting another child.

Apparently her wardrobe plans for an upcoming event let the baby bump, I mean, cat out of the bag.

"It looks like Heidi is four months pregnant,” an insider tells In Touch Weekly. "Sketches leaked online of her in redesigned couture gowns to make room for a bump, but were quickly taken down!”

Klum, 35, has three children -

Leni Henry Johan

, 2. Henry and Johan are Seal's biological children.

"She plans to announce her pregnancy when she wears the dress [from the leaked photos] to the event," the insider said.

| Lisa Gutierrez, The Star