Britney Spears sympathised with Kim Kardashian during her pregnancy after the reality Tv star was savaged by critics over her weight gain.

Kanye West's new fiancee came under attack earlier this year (13) as she piled on the pounds while expecting her first child, daughter North West, and the harsh comments caused the socialite to break down in tears on her show Keeping Up with the Kardashians.

Spears admits her heart went out to Kardashian after tuning in to the episode, and she couldn't help but feel sorry for the then mother-to-be because the Toxic hitmaker treasured the time when she was expecting her two sons with ex-husband Kevin Federline.

She tells InStyle magazine, "I was like, 'Bless her heart', because I remember that time... That should be the time when your body is most treasured."

Getting candid, Spears adds, "I loved being pregnant for so many reasons, not to mention the sex is awesome then."

Meanwhile, in another interview with Britain's Telegraph newspaper, the pop superstar admits her own reality show with Federline, Britney and Kevin: Chaotic, was a big mistake.

She says, "I would never do something like that again. Actually, that was really bad. That was probably the worst thing I've done in my career."

The show, made from home videos throughout 2005, was panned by critics and only ran for five episodes.