From Vatican News: 

Concluding the General Audience on Wednesday morning Pope Francis asked the faithful for a “special prayer” for his 95-year-old predecessor, the Pope Emeritus Benedict XVI: “May the Lord sustain him in this witness of love for the Church until the end”.

Answering questions put to him by journalists, the director of the Vatican Press Office, Matteo Bruni confirmed that “In the last few hours there has been an aggravation of his health due to advancing age.”

He added that the situation “at the moment remains under control,” and that the Pope Emeritus is constantly monitored by doctors.

Bruni also said that after the General Audience in the Paul VI Hall, Pope Francis went to the Mater Ecclesiae monastery in the Vatican where Benedict XVI resides.

“We join him in prayer for the Pope Emeritus,” Bruni said.