Klum lent her name and face to a line of women's wear and baby-wear marketed by the company for more than a year. She's been featured on several of Otto's mail order catalogues.
"Otto has made use of a clause and canceled my contract because I'm pregnant," Klum claimed, on her website.
However, Otto denies the claims, saying Klum's contract was canceled because she missed an important meeting.
A spokesman for Klum said no legal action is planned.