Chelsea Clinton has given birth to a baby boy, the former first daughter announced on Twitter.
Clinton tweeted the news on Saturday morning, writing that she and husband Marc Mevinsky were "overwhelmed with gratitude and love as we celebrate the birth of our son, Aidan Clinton Mevinsky."
In a statement, former President Bill Clinton and presumptive Democratic presidential nominee Hillary Clinton said they are "overjoyed" to be grandparents again," adding that Chelsea and the baby "are both doing well and enjoying this very special time together."
The 35-year-old announced in December 2015 she was expecting her second child.
"Charlotte is going to be a big sister! Feeling very blessed & grateful this holiday season," Clinton wrote on Twitter at the time, keeping the baby's gender under wraps.
While campaigning for her mother's White House bid in New Hampshire earlier this year, Clinton said she has tried to follow her parents' example in raising her 21-month-old daughter, describing her own upbringing.
"I know she doesn't really understand what's happening, but I talk to her about the news every day," Chelsea Clinton said. "I talked to her on Sunday evening about why I had to be gone for a few days to support her grandmother because it's really important for her future."
The younger Clinton is married to hedge fund manager Marc Mezvinsky, the son of former U.S. congressman Edward Mezvinsky and former U.S. congresswoman Marjorie Margolies-Mezvinsky.