Former US President George H.W. Bush has been re-admitted to a hospital in Houston, Texas, for a recurrence of pneumonia.
Bush, 92, has been at Methodist Hospital since Friday, his spokesman Jim McGrath said in a statement on Tuesday.
A source close to Bush said he will probably be kept at the hospital for several more days for medical observation.
Bush has suffered from poor health in recent years. In January, he spent 16 days at the same hospital in Houston being treated for pneumonia. During that time, he was on a ventilator and was in ICU.
He was also hospitalized in 2015 after falling at his summer home in Kennebunkport, Maine, and breaking a bone in his neck.
In 2014, he was hospitalized in Houston for about a week for shortness of breath. He also spent Christmas 2012 in intensive care for a bronchitis-related cough and other issues.
Bush has a form of Parkinson's disease and uses a motorized scooter or a wheelchair for mobility.
The 41st president is also referred to as "Bush 41", "Bush the Elder" and "Bush Senior" to distinguish him from his eldest son, George W. Bush, who became the 43rd US president.
Bush served as US president from 1989 to 1993, and was vice president from 1981 to 1989 during the 8-year administration of former President Ronald Reagan.