Former U.S. President George Herbert Walker Bush has been taken to a Houston hospital Tuesday evening as a precautionary measure to monitor his health.

The 41st president experienced shortness of breath, which led to an ambulance ride to the Houston Methodist Hospital. Bush's staff released a statement about his condition.

"President Bush was taken by ambulance to the Houston Methodist Hospital as a precaution after experiencing a shortness of breath earlier this evening," the statement said. "The former president, age 90, will be held for observation, again as a precaution."

According to USA Today, Bush is the oldest living former president and vice president. In addition, he is also the last living former president who served in World War II.

ABC News reported that Houston Methodist is the same hospital where Bush spent nearly two months for a bronchitis-related cough and other issues from November 2012 to January 2013. President Barack Obama has been notified of Bush's condition.

"The President has been made aware that President Bush was admitted to the hospital. President Obama and the First Lady send their good wishes to the former President and the entire Bush family during this holiday season," White House Spokesperson Eric Schultz said in a statement tonight.

Bush's most recent appearance, according to USA Today, was at an event in November at Texas A&M University with his son, former President George W. Bush. He appeared seated in a wheelchair, given that he can no longer use his legs.

ABC News reported on the history of Bush's health problems. Back in 1991, when he served as president, Bush entered the hospital with an irregular heartbeat; it popped up again in February 2000.

"Bush experienced a recurrence of the irregular heartbeat in February 2000, when he was attending a reception in Naples, Fla.," ABC News wrote. "He spent a night in the hospital, but smiled and joked with reporters the next day."

Doctors also diagnosed him with a thyroid condition known as Graves Disease. According to ABC News, his wife, Barbara Bush, also had the thyroid disease.

Although his family lamented publicly that the former president can no longer walk unassisted, Bush has engaged in an active lifestyle whenever possible, which has included golf, fishing, jogging, and power walks at his Maine summer home. He celebrated his 90th birthday with a tandem parachute jump near his summer home in Maine; ABC News noted that he also did this to mark his 75th, 80th, and 85th birthdays too.