CBS News correspondent Bill Whitaker reported Wednesday the couple confirmed the news on Preston's website, saying, "It's impossible to keep a secret ...Especially one as wonderful as this."
Photos: John Travolta
John Travolta's 16-year-old Son Dies In Bahamas
Preston, 47, is now three months pregnant. Travolta is 56. The gossip magazine Star first broke the story.
Heidi Parker, of Star, said, "Kelly Preston's pregnancy is a huge shocker. It's a big deal in Hollywood because it's almost like the perfect movie; they had a terrible loss now they're having a miracle in their lives."
Whitaker noted it was in January of 2009 when the family suffered the devastating death of their first born, Jett. The 16-year-old collapsed after having a seizure at their vacation villa in the Bahamas.
To add to their pain, the ambulance driver who transported Jett, allegedly demanded $25 million from John Travolta, threatening to release documents relating to Jett's final hours.
At the extortion trial in September, Travolta testified how he frantically tried to revive his dying son. For the first time, he revealed that Jett was autistic and endured a lifetime of seizures.
Parker said, "They've suffered a lot in the last year. They've been grieving, They've had a very difficult time."
And just last week, the family suffered another terrible loss when two of their dogs died after being hit by a truck at an airport in Maine.
The Travoltas appear on the cover of Star magazine with the headline reading "Miracle Babies." Parker, referring to the cover, said, "John and Kelly, miracle baby. I mean this is incredible for them. What a nice experience for this family that's been through so much."
Family has always come first for the Travoltas who recently starred in "Old Dogs" with their 10-year-old daughter, Ella Bleu. Preston has often shared her love of motherhood, telling the website iParenting.com, "I've wanted to have babies since I was 11."
The baby is due in November.
Gossip reporter Paula Froelich said on "The Early Show" she thinks Preston and Travolta got some help.
"(The pregnancy) is not a shock to anyone in their camp."
Froelich told "Early Show" co-anchor Maggie Rodriguez the Travoltas are not like average parents in Hollywood. She said they were really focused on raising their kids -- a practice that isn't that common among celebrities.
Since Jett's death, Froelich said the couple likely made a "concerted effort" to have another child together.
She added the couple has dealt with their grief differently than other stars. Instead of taking their grief to the front of magazines, the Travoltas, she said, have kept to themselves.
Froelich added the Travoltas' daughter Ella is "pretty excited" to have the chance to have a new sibling.