Khloe Kardashian Cracks a Smile at 6 Months Pregnant, Says She Works Out When She Can

Khloe Kardashian's facing a big challenge in keeping her revenge body -- pregnancy -- but she's still giving it her best shot.

We got the mom-to-be at LAX Wednesday and asked her some tough questions about staying fit during pregnancy ... but even Khloe doesn't have all the answers.

Even so, she tells us she's exercising when she feels up to it and seems to be in great spirits ... all good news for mama and baby. Still no official reveal on whether she's having a boy or a girl, though.

As we reported ... Khloe and Cavs star Tristan Thompson are expecting sometime around late March, and he agrees with us -- she looks bomb at 6 months.

Season 2 of 'Revenge Body' premieres Sunday.