John Travolta and Kelly Preston will call their new baby boy Benjamin.

Kelly, 48, is due to give birth in less than three weeks and 'Saturday Night Fever' star John has revealed the excited couple have already chosen a name for their son, according to America's Star magazine.

Speaking in Brisbane Australia on Monday - where the flying enthusiast flew to celebrate Quantas Airlines 90th anniversary - John said "he is due to be born in 19 days" before revealing the name.

The couple announced the pregnancy in May, saying: "It's impossible to keep a secret ... especially one as wonderful as this. We want to be the first to share this great news with everyone that we are expecting a new addition to our family."

Friends have called the new addition to the Travolta family a "healing baby" after the couple's 16-year-old son Jett died almost two years ago when he suffered a seizure during a family holiday to the Bahamas.

John - who also has a 10-year-old daughter Ella Bleu with Kelly - has described the moment they found out she was expecting another baby as "a miracle".

The 56-year-old actor explained: "We tried for several years, and we didn't think it was going to happen for us.

"This is a miracle, and we feel blessed and we are so moved by the generous outpouring of support and goodwill we've received from people all over the world."