The couple - who married in September 2009 and star in their own reality TV show, 'Khloe and Lamar' - have been trying to get pregnant ever since they tied the knot but now basketball star Lamar wants them to stop so he can concentrate on his career.
A source close to Lamar - who recently moved to the Los Angeles Clippers after being traded from the Dallas Mavericks - said: ''Khloe and Lamar are taking a break from trying to have a baby while he settles into his new job back in LA. Lamar said that he and Khloe were trying for a baby, but admitted that he's not ready because he needs to give his all to his game.''
While Khloe is supportive of his decision, she is blaming herself for the situation.
The source added to America's In Touch magazine: ''Khloe feels like a failure.''
Khloe - who is thought to have undergone fertility treatment - has made no secret of her desire to have a baby but admits she was feeling under pressure to conceive.
Speaking last year, she said: ''People keep saying, 'Why aren't you pregnant yet?' That's what scares me, when people are like, 'Did you go to the doctor? Do you know if everything's working?' It's nerve-racking. Sometimes I feel like I'm letting everyone down.''
Lamar already has two children, Destiny, 13, and 10-year-old Lamar Jr., from a previous relationship.