She told host Nick Grimshaw on the program, "I was hospitalized. It was just kind of a bad pregnancy, so I had to take off way more time than normal."
While she doesn't give us a lot of details in the latest interview (and admits that the experience hasn't scared her off from wanting baby number two "...in like a year"), we know she struggled with acute morning sickness, as she gave plenty of candid interviews on the topic throughout her pregnancy with daughter River Rose.
"I vomit a good dozen times a day. It's like bad. I vomited before coming out here," she told Ellen DeGeneres in December 2013. "I'm not even kidding, it's so bad. It's so bad. It's, like, so gross."
She added, "My nails are short, my hair still falls out—it's not all lush and beautiful. And I have no glow. Unless it's, like, something left over from a bad throw up. It's horrible."
Clarkson, of course, isn't the only mom in the public eye to have a tough go of pregnancy. Kate Middleton famously suffered hyperemesis gravidarum, or morning sickness so severe as to be debilitating. Gwyneth Paltrow, Molly Sims, Mariah Carey, and Kate Winslet are also all among the stars who have copped to suffering bad morning sickness during their pregnancies.
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Photo courtesy of Instagram/KellyClarkson