Brady's mother, Galynn, told the Associated Press on Friday that she had no comment on the report. The supermodel's agent at IMG, Anne Nelson, says she doesn't comment on the personal lives of her clients.
Brady has a son, Jack, with actress Bridget Moynahan.
Late last month, the New England Patriots player said Bundchen was not pregnant. "One is enough," Brady said on May 28. "I have dogs, and that's all I need."
"Family is everything," Bündchen, who turns 29 next month, told People last month. "I think family is the base to everything. I think that is one of the things I'm most grateful for. I have a lot to be grateful for but I think that's definitely number one."
RadarOnline.com has reported that Bundchen was telling friends she's pregnant.