(Reuters) - Chelsea Clinton announced on Thursday that she is pregnant with the first grandchild of former President Bill Clinton and former Secretary of State Hillary Clinton.

"Marc and I are very excited that we have our first child arriving later this year," said Chelsea Clinton, 34, referring to her investment banker husband, Marc Mezvinsky, 36.

Sitting with her mother in side-by-side armchairs on a stage at a New York City event on empowering women, Clinton delivered the news with a broad smile.

The audience at "Girls: A No Ceilings Conversation," organized by the Bill, Hillary & Chelsea Clinton Foundation, immediately broke into applause and cheers.

"I certainly feel all the better whether it's a girl or a boy that she or he will grow up in a world full of so many strong young female leaders," said Chelsea Clinton, who works for the family foundation and is a correspondent for NBC News.

"Thank you for inspiring me and thank you for inspiring future generations, including the one that we'll be lucky enough to welcome into our family later this year," she told the audience.

It was unclear how news of the first Clinton grandchild will affect the political ambitions of grandmother-to-be Hillary Clinton, who is considering a run for the White House in 2016.

Former president Clinton told reporters in Davos, Switzerland, in 2011: "I would like to have a happy wife, and she won't be unless she's a grandmother... It's something she wants more than she wanted to be president."

Both expectant grandparents immediately took to Twitter to share their happy news.

Bill Clinton tweeted: "Excited to add a new line to my Twitter bio...grandfather-to-be! @hillaryclinton and I are so happy for Chelsea and Marc!

An equally thrilled Hillary Clinton tweeted: "My most exciting title yet: Grandmother-To-Be! @billclinton and I are thrilled that Chelsea and Marc are expecting their first child!"

(Additional reporting by Jonathan Allen; Editing by Paul Thomasch and Gunna Dickson)

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