By peoplestaff225
Updated November 21, 2008 10:00 AM

After revealing that she’s hoping to expand her family with country singer Keith Urban even further, the rumors that Nicole Kidman is already expecting another baby were swirling after her appearance at the premiere of her new movie, Australia. The 41-year-old actress immediately denied the claims, saying she simply has "a little tummy" and blames the speculation on family genetics! "I think I’ve always had a little tummy, though, it runs in the family. My sister does, my mum does, my grandmother did…We affectionately refer to it as the ‘little tummy,’" explains Nicole. However, despite her willingness to offer an explanation, the new mom is quick to remind everyone that none should be needed — she just gave birth!

As more children are not in the immediate future, Nicole is focusing all of her energy on her 4-month-old daughter Sunday Rose. "Completely besotted with [Sunday]," Nicole — who can’t stand to be away from her baby girl — shares that her daughter has "just discovered her voice," making the proud mama privy to many private performances.

In addition to Sunday, Nicole also has daughter Isabella Jane, 15, and son Connor Antony, 13, with ex-husband Tom Cruise.

Australia opens November 26th.

Source: PEOPLE