During her interview Salma revealed that she took up smoking during the filming of Frida, her biopic of Mexican artist Frida Kahlo, but was able to kick the habit after falling pregnant with her now four-year-old daughter Valentina.
The sexy star also revealed than a severe injury has hampered her since July 2010 - while she was getting ready to go to a party to watch the World Cup soccer match between Spain and The Netherlands she slipped and tore two ligaments in her ankle.
"I broke two ligaments last year during the World Cup. I was actually in my bathroom, barefoot. I was not skiing or playing soccer. I don't know how you twist an ankle and I broke two ligaments,"she says.
"But I had to make it to my friend's because I had run out of electricity in my house - everything was going wrong that day - and finally I made it to watch the game between Spain and Holland."
Salma says she should have sought medical attention - but she exclaimed, "I was not gonna miss that soccer game!"
She made it to the party to watch the game, but her ankle has caused numerous problems since then and she refuses to have surgery.
[N]ow every six months, when I need it the most, something happens [to her ankle] again," she says. "Six months ago I was going to play this prostitute on this French movie, and of course she was a stripper also, so she needed the big high heels. Two days before we start... I twist it.
"The worst part about it is you can't wear heels. You've never been a Mexican short woman!" she said to Letterman. "This is tragic - I often say, had it not been for high heels, I would still be in Coatzacoalcos [town in Mexico] with 10 kids and this big!"