Kelly Preston's mom, Linda Carlson, tells UsMagazine.com she "burst into tears" when she heard her daughter was pregnant with her third child at age 47.
"I cried so hard I couldn't see straight, just bawled my eyes out," she said. "Because I've been so worried about her! When they're that unhappy. I could cry right now remembering."
Preston and her husband John Travolta, 56, lost their son, Jett, after he suffered a seizure in January 2009. (They are also parents to 10-year-old daughter, Ella Bleu.) They were then extorted by the Bahamian paramedics who first responded to the call.
Carlson says the new addition will know all about Jett.
"He'll see the pictures and he'll be told stories. He or she, whatever," said Carlson. "It couldn't come at a better time. Her aura is so filled with peace. It's changed their lives."
PHOTOS: Hollywood's hottest married couples
Carlson admits her daughter and Travolta have "been through so much. Not only losing Jett but those godawful horrible men trying to extort them! Unbelievable. It was awful on them, they were grieving so badly. They do weather it, but holy cow, such grief. John was devastated, just devastated."
Continued Carlson, "We are over the moon I've been praying that this would happen. Especially since Jett's death. Anything to get them out of their sorrow. I know Kelly has been longing for another baby. She just loves babies! So do I. I just can't wait for this child to arrive. It's taken them out of such deep grief and made them able to focus on new life. It just couldn't come at a better time."
She says Preston's pregnancy was a "surprise" even though they had "been trying."
Preston announced the news at a family lunch shortly after her brother, Chris, revealed he was engaged.
PHOTOS: See touching pics of John and his son, Jett
"She just said 'I'm pregnant!' and it just spilled out," Carlson recalled. "And I burst into tears and I had to go over and just embrace her. I was so thrilled I couldn't see straight."
And Preston is shrugging off pregnancy complications due to her age.
"She's not worried about it at all. She's not concerned," Carlson said. "She takes really good care of herself and she's in good health. She looks so much younger."