The couple welcomed daughter North in June, 2013, and the reality TV superstar admits she has been trying everything to get pregnant again.

But she tells E! News her recent boast that she and her husband have sex up to 500 times a day may be the problem.

She says, "I've done everything so perfect to try and get pregnant. There's a list of things you shouldn't be doing and I was perfect for eight to 10 months and now I don't understand.

"Literally, teenagers on meth get pregnant in two seconds. It's crazy. When you don't want to be pregnant, it happens.

"The doctor said he thinks I'm having sex too much. He said one time is more powerful."