Kim Kardashian isn't rushing to have her own baby like big sis Kourtney.
"Let's just say Mason is the best birth control ever!" the E! reality star, 29, joked on Ryan Seacrest's KIIS-FM radio show Thursday morning. "I'm definitely happy to wait awhile."
VIDEO: Kourtney and Khloe get in an ugly catfight
(She's changed her tune from this Sunday's episode of Kourtney & Khloe Take Miami, where, according to a clip played on the radio show, she says, "I seriously thought by the time I was 30, I would have one [baby] and a bun in the oven... Mason is the cutest baby in the entire world! I cannot wait to have a baby just like him.")
Kim, her new beau, Dallas Cowboys' Miles Austin, her sisters and Mason have been on vacation in Mexico.
PHOTOS: The Kardashians as kids
"Mason came. It was fun. He loves the beach and the ocean," said Kim.
She had less to say about Austin, 26.
"I am having a really good time. I am living my life... and nothing I want to tell you!" she said coyly. "I'm single and I'm having a good time. You're making it really awkward, Ryan! I'm having a good time, meeting some really great people and trying to live my life... probably a lot more private than I was before!"
Us Weekly has reported the two -- who hooked up in June, about two months after she split from Reggie Bush -- are taking it slow.
PHOTOS: Kim and Reggie: The way they were
"They are dating," said a source close to her, "but she doesn't want to rush anything."