The birth comes amid unrelenting speculation that Clinton is likely to make a 2016 bid for the US presidency.
Hillary Clinton’s Twitter bio reads: “Wife, mom, lawyer, women & kids advocate, FLOAR, FLOTUS, US Senator, SecState, author, dog owner, hair icon, pantsuit aficionado, glass ceiling cracker, TBD...”
POTUS may well be added to the list one day but the former US Secretary of State says that becoming a grandmother is her "most exciting title yet”.
The Clintons have released a statement saying, "We are blessed, grateful, and so happy to be the grandparents of a beautiful girl, Charlotte Clinton Mezvinsky, born on Friday evening, September 26, 2014.
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"We are thrilled to be with our daughter and her husband as they welcome their daughter into the world.
"Chelsea is well and glowing. Marc is bursting with pride. Charlotte's life is off to a good start.''
Chelsea Clinton and husband Marc Mezvinsky announced the birth of their daughter early on Saturday, Eastern US time, posting just after midnight: "Marc and I are full of love, awe and gratitude as we celebrate the birth of our daughter, Charlotte Clinton Mezvinsky."
