Kelly Preston didn't consider the health risks of being an older mother when contemplating having another child.

The 48-year-old actress gave birth to Benjamin - her son with husband John Travolta - in November but admitted although she knew it would be "difficult" to conceive at her age, she never worried about the implications of getting pregnant in her late forties.

She said: "I didn't consider this risk. I just considered that it was difficult. I never thought that would be me at all. So, I think we're just really happy that we're so fortunate."

Kelly and John's eldest child, 16-year-old Jett tragically passed away two years ago when he suffered a seizure while on a family holiday in the Bahamas and the actress - who also has a daughter Ella Bleu, 10, with her spouse - revealed Benjamin has helped the entire family to cope with their loss.

She told the 'Today Show': "It's been wonderfully healing. Of course, you know, we still - it's still every day. But it's been, I think, a really nice gift for a lot of people throughout the world.

"We've gotten the most beautiful letters. And the most beautiful notes of happiness. And I think -- just sort of a sigh of relief, a bit. And that's been really nice to sort of share that with people."

Kelly stars in new film 'Casino Jack' with Kevin Spacey and although returning to work after Jett's death was difficult she explained her co-star helped her through it.

She said: "Kevin was a lifesaver, really. I mean, at that point, I really didn't want to go back to work. But they condensed my work down to a couple of weeks, which was really nice.

"But every day, he's so... he's so naturally funny. And he made me laugh. And that was the greatest - the greatest gift he could've given to me while we were working."