"There's nothing to announce. That's just a couple of pounds," she said during an interview on Australia's Kyle and Jackie O Show.
The rumour mill went into overdrive last week when Jennifer stepped out for the New York premiere of her new film We're The Millers showing off a slightly rounded tummy.
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The actress also put paid to rumours that the party she threw for fiancé Justin Theroux over the weekend to celebrate his 42nd birthday was actually a secret wedding ceremony.
"I've had helicopter divebombing the house today," she said. "It's fine – it's totally fine. There's no wedding this weekend – you heard it first here!"
She expressed her frustration at the world's interest in her private life. "It does feel a bit like they've exhausted the question, and also the speculations," she said.
"It's all been pretty much exhausted. I just think, 'Why not just wait until we have the fun of announcing something instead of playing the guessing game', whether it be family, weddings, this, that, the other thing," she added.
Jennifer threw her fiancé a birthday bash exactly one year after the couple got engaged.
A fleet of cars pulled up to the lovebirds' £13million Bel-Air mansion, as a host of Jennifer and Justin's celebrity friends including Don Cheadle, Jason Bateman, Ellen Degeneres and her wife Portia De Rossi attended the star-studded party .
Fans of the couple are waiting to see Jennifer and Justin become husband and wife , but Jennifer has revealed that she is in no rush to walk down the aisle and quashed rumours that they had called off the wedding.
"We just want to do it when it's perfect, and we're not rushed, and no one is rushing from a job or rushing to a job," she said.
"We have yet to set any date. There have been no cancelled weddings. There have been no postponed weddings. There have been no arguments about where to get married. Just clearing all that up."