Bush was admitted to Houston Methodist Hospital earlier this month after a persistent cough led to a pneumonia diagnosis, according to his staff.
This week, Bush's physician, Dr. Clint Doerr, a pulmonologist at Houston Methodist Hospital, said the former president was still in the hospital due to "chronic bronchitis."
“While President Bush has recovered from pneumonia, he continues to deal with the effects of chronic bronchitis, which is a condition more prevalent with age. This means his airway has a constant, low-level of inflammation that can aggravate the symptoms of pneumonia," Doerr said in a statement.
Doerr said Bush is expected to continue "aggressive respiratory treatments" to help treat the effects of chronic bronchitis after being discharged.
ABC News' Gina Sunseri contributed to this report.