Newlywed Kelly Clarkson is set to become a first-time mum.

The Since U Been Gone singer tied the knot with Brandon Blackstock last month (Oct13), and has made it no secret she wants to expand their family right away.

And, on Tuesday (19Nov13), Clarkson took to Twitter.com to share the exciting news, writing, "I'm pregnant!!! Brandon and I are so excited! Best early Christmas present ever."

Just last week (11Nov13), Clarkson sparked rumours about a pregnancy during an appearance on The Late Show with Jay Leno in America, when he inquired about her desire to have a child.

The star joked "practice makes perfect" and confessed she and her new husband are having sex "like rabbits".

But Leno wouldn't let up as he tried to coax an announcement out of his guest, boldly asking Clarkson, "Are you pregnant right now?"

The singer responded, "What are you saying?", before adding, "We are not announcing anything right now."

Last month (Oct13), the American Idol winner revealed her 2013 Christmas wish was to be pregnant for the holidays.

She is already stepmother to Blackstock's two children from a previous relationship.