John Travolta, 56, and his wife Kelly Preston, 47, are expecting another baby, they have revealed to people.com.

The couple, who lost their 16-year-old son Jett to a seizure last year, also announced the news on their respective websites.

"It's impossible to keep a secret ... especially one as wonderful as this," a statement on John Travolta's official website reads.

"We want to be the first to share this great news with everyone that we are expecting a new addition to our family."

The couple also have a 10-year-old daughter, Ella.

- NZ HERALD STAFF