Chelsea Clinton has welcomed a son.

Chelsea, 36, announced on Twitter on Saturday (18Jun16) that she and husband Marc Mezvinsky, 38, had welcomed a baby boy named Aidan Clinton Mezvinsky.

“Marc and I are overwhelmed with gratitude and love as we celebrate the birth of our son,” she wrote on the social network.

Aidan is the couple's second child, joining 20-month-old big sister Charlotte as the newest member of their family.

The former broadcaster, who is the daughter of former President Bill Clinton and current U.S presidential candidate Hillary Clinton, revealed she was pregnant last December (15).

2016 is shaping up to be a big year for the Clinton family, as Aidan's grandmother Hillary looks set to contest November's (16) presidential election for America's Democratic Party against the Republican Party's Donald Trump.