Khloe Kardashian: Scott Has Changed Since Getting Kourtney Pregnant

In light of 's pregnancy, Scott Disick, 25, has changed, says her sister Khloe.

Though the couple split in February after she suspected him of cheating, "he's always been obsessed with Kourtney," Khloe told Usmagzine.com Sunday at a pool party at Wet Republic in Las Vegas to promote their new E! show Kourtney and Khloe Take Miami.

These days, "he's more – well, I don't know if a man can be maternal, but he's definitely becoming more maternal," Khloe added. ("Paternal," Kourtney, 30, corrected her.)

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She said she isn't sure they'll wed.

"I feel like there's just so much in my mind, and I have so much to plan and think about for the baby," she said. "I will worry about myself later."

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As for her pregnancy, she said, "I feel good."

She said she hasn't had any weird cravings. "I have more healthy cravings than my normal eating habits," she said. "I crave fruit and smoothies. I mean, I definitely eat junk. Yesterday, I laid in bed and ate Pinkberry and Twizzlers and Mexican food. I mix it up."

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Kourtney – who is due in December – said she's gained about 10 pounds so far.

"I'm embracing it," she said. "I like when my body changes. I like seeing it. I run around naked all day at home. I think it's like a beautiful thing."

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She said she doesn't know yet if she's having a boy or girl.

Though filming on their new Miami show has wrapped, "we're taping season four of Keeping up with the Kardashians which we've already filmed a little bit for and we start fully taping in September," Kourtney said.