"I'm having a baby ... wait I want to finish ... with Ellen," UsMagazine.com said the 46-year-old talk-show host quipped in the interview, which is to air Wednesday.
"No, I decided to have the first one with my wife. We got married in July and, you know, it's interesting. It's disgusting the way babies are made."
"Good for you," DeGeneres said. "And why is it disgusting?"
"Well, there are so many human body parts involved," Kimmel joked. "Did you know there are eggs in us? That's gross just to start with."
The comedian said he and his wife don't know the baby's gender yet. Kimmel also has a 20-year-old son and 22-year-old daughter with his ex-wife Gina, whom he divorced in 2002.