Because the Clintons are *so* close, Hillary apparently kept her “pneumonia” diagnosis secret even from her daughter.

That’s what Chelsea Clinton revealed to Cosmopolitan magazine in an interview published on Wednesday.

“Well, I didn’t know that she had pneumonia. I didn’t know she had pneumonia until she came over to my apartment,” Chelsea said.

“So I don’t think it was a conscious choice. I mean, she didn’t even tell me. I think she just expected she would power through it as she has always powered through everything. As her daughter, I wish she would have listened to her doctor and taken a couple days off when her doctor told her she needed to get some rest, and I’m grateful she did finally listen to her doctor and she took a couple days off.”

But despite that level of secrecy — and inviting speculation that Hillary could be hiding other conditions — Chelsea claimed her mother is actually healthier than she is.

“And I think it was clear last night that she is — you know, she certainly looks healthier at her age than I feel at 36 at this moment,” she said, referring to the debate.

“I loved her answer about stamina, and yes, I think when anyone has traveled to 112 countries and a million miles, and sat through 11 hours of congressional hearings all in one day, they can then kind of have that conversation with my mom. But until then, I think that she wins that argument any and every day.”