Back on the campaign trail after taking a few days off to recover from pneumonia, Hillary Clinton joked that her illness "finally got some Republicans interested in women's health."

Republicans have been questioning the Democratic presidential nominee's health and stamina in recent weeks, implying that Clinton might not be fit for the White House.

"As the world knows, I was a little under the weather recently," Clinton said in a speech to the Black Women's Agenda Symposium. "The good news is, my pneumonia finally got some Republicans interested in women's health."

Clinton on illness: "The good news is my pneumonia finally got some Republicans interested in women's health" https://t.co/3cffgHGrmV — ABC News Politics (@ABCPolitics) September 16, 2016

Clinton was diagnosed with pneumonia last Friday, but her campaign didn't disclose her illness until Sunday, when she had to leave a 9/11 memorial event early because she wasn't feeling well.

She returned to the campaign trail Thursday after taking a few days off to rest.