Chelsea Clinton said she didn’t know Hillary Clinton had pneumonia until she stumbled out of a 9/11 commemoration ceremony.

During an interview with Cosmopolitan published Wednesday, the daughter of the Democratic nominee was asked why her mother didn’t disclose her illness to voters sooner when Chelsea admitted that not even she knew about it.

[dcquiz] “Well, I didn’t know that she had pneumonia,” Clinton told the magazine. “I didn’t know she had pneumonia until she came over to my apartment.” (RELATED: Clinton Foundation Staffers Brace Themsleves For Dozens Of Layoffs)

“So I don’t think it was a conscious choice,” she continued. “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.”

“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.”

“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.” (RELATED: Chelsea Clinton Goes After Donald Trump While Campaigning For Hillary Clinton)

“But until then, I think that she wins that argument any and every day.