So far, their due dates seem to be the only thing in common between their pregnancies. Middleton battled acute morning sickness early on, but Kardashian told Hoda Kotb and Kathie Lee Gifford that she's feeling good and hasn't "been sick or anything."
And Kardashian has had to face some harsh criticism over her pregnancy with boyfriend Kanye West, since she is still legally married Kris Humphries. (Kardashian filed for divorce from the NBA player in October 2011 after 72 days of marriage.)
"It's been a year-and-a-half since I filed, so I definitely waited six months before I started a relationship," the Kourtney and Kim Take Miami star explained on TODAY in response in her defense. "I'm 32 years old and -- you'll see in the season -- there's been a lot of fertility issues that I haven't really spoken about, so it's kind of a miracle that I did get pregnant. I think God puts things in front of you, and places things in your life, for a reason."
But Gifford pointed out that there's "a chance" this child could be born while she's still married to Humphries, 27. "I hope not," Kardashian said. "I'm really hopeful, and I'm just hoping to get through it sooner than later . . . it's a process."
What advice will she be taking from sister Kourtney -- mother to son Mason, 3, and daughter Penelope, 6 months, with boyfriend Scott Disick -- on motherhood? "I'm definitely going to be a different mom than Kourtney," she said. "I'm going to share my bedroom with my boyfriend unlike her . . . she loves to have the babies sleep in bed with her at night."