The Fashion Police star commented that the popstar's recent fashion and hair choices point towards a possible pregnancy.
"I think she is pregnant because she has been covering up this part of her body recently and I have been noticing that a lot," she said on Alan Carr's Chatty Man.
"And her style has changed and you can't bleach your hair blonde when you are pregnant."
Osbourne also played down reports linking her to the presenter job for The X Factor USA.
"Everybody keeps talking about it. I have not spoken to Simon [Cowell]. Of course if he wanted me it would be such an honour but there are probably better people than me."
Speaking about her younger brother Jack Osbourne's recent MS diagnosis, she added: "I am so proud of him for standing up and letting the world know he has MS; there is such a misconception about it."
Lady GaGa - who is currently dating Vampire Diaries star Taylor Kinney - said back in 2009 that she plans to start a family in ten years' time.
Alan Carr's Chatty Man continues tomorrow (September 21) at 9pm on Channel 4.