Chelsea Clinton is a mom again.
She announced the arrival of son Aidan Clinton Mezvinsky late Saturday morning on Twitter.
Baby Aidan joins big sister Charlotte, who turns 2 on Sept. 26.
The 36-year-old Clinton, who announced her second pregnancy in late December, has been campaigning on behalf of her mother, presumptive Democratic presidential nominee Hillary Clinton. She is also on the board at her family’s foundation.
She married Marc Mezvinsky in 2010. He is also a fellow Stanford alumnus and the scion of a political family. His parents, Edward and Marjorie, both served in Congress.