Kim Kardashian had a lot of sex on the premiere of the tenth season of "Keeping Up With the Kardashians, " or at least we heard she had a lot of sex.

The 34-year-old reality star and husband Kanye West welcomed their first child North West in June 2013 , but getting pregnant the second time around seems to be proving more difficult for the couple.

The episode opens with Kim lying in bed, surrounded by her sisters Kourtney, Khloe and Kendall. While she's lounging, she tells them that it's doctor's orders to stay horizontal after having sex:

"The doctor said when I have sex I have to lay down for, like, 10 to 20 minutes, and I just had sex before you guys got here. I swear, Kim says. He said it takes 10 minutes for a sperm to swim up there. Ill wait, like, five more minutes for this to marinate ... inside of me.

Later in the episode, Kim tells Khloe that she and Kanye managed to sneak in a 10-minute quickie -- in the bathroom of her latest nude photo shoot -- since it was all about timing.

"I was like, Im ovulating today! so I made him come to my photo shoot, Kim tells Khloe. I don't feel bad about that for one second. Theres only a 20 percent chance of getting pregnant every month. I know that Im ovulating right now, so you gotta get it in when you can get it in."

Later, Kim visits Khloe at her house and as she collapses on a chaise she declares , "Literally, I'm so exhausted. I've been having sex 500 times a day."

Baby-making is clearly a tiring business, and in a preview for the season's future episodes, the reality star mentions she and Kanye may need to find a surrogate.