Former President George H. W. Bush was taken to a hospital in Houston on Tuesday night as a precautionary measure after experiencing shortness of breath, according to a statement from his office.
“The former president, age 90, will be held for observation, again as a precaution," according to spokesman Jim McGrath.
Bush served as the nation's 41st President and is the father of 43rd President George W. Bush.
Bush, a Republican, was previously hospitalized in November 2012 with bronchitis but recovered after two months.
Before becoming President, Bush "senior" served as vice president under Ronald Reagan.
He is also a former Navy pilot and flew 58 combat missions in World War II in the Pacific.
Bush was shot down once but was rescued by U.S. sailors, according to his White House biography. He received the Distinguished Flying Cross.
Bush became known for his declaration that the United States should become "a kinder and gentler nation."
Before going into politics, Bush worked in the Texas oil industry.
President Barack Obama was told about Bush's hospitalization, White House spokesman Eric Schultz said.
"President Obama and the first lady send their good wishes to the former President and the entire Bush family during this holiday season," he said.