The fractured neck bone suffered by former President George H.W. Bush when he fell at his summer home will be allowed to heal on its own, a recovery that could take three to four months, officials said.

Bush, at 91 the oldest living former president, did not suffer any neurological impairment when he took a spill at his home in Kennebunkport on Wednesday. He remained hospitalized in fair condition on Thursday.

Bush spokesman Jim McGrath said the 41st president never lost consciousness and was being fitted with a brace to immobilize his neck. He fractured his C2 vertebra, the second one below the skull, but it didn't impinge on his spine and didn't lead to any neurological deficits, McGrath said.

Bush is being treated at Maine Medical Center, the state's largest medical facility, where a children's hospital is named for his wife. His family declined to say how he fell.

Dr. William D'Angelo, a neurosurgeon who is treating Bush, said the former president was lucky the fracture wasn't more serious.

"He's in great spirits," D'Angelo said outside the hospital. "He's with family. As his wife said, it takes a lot more than this to knock his spirits down. He was shot down over the Pacific in World War II. She said this is a small bump in the road."

A hospital spokesman said it was premature to speculate about when Bush will be released, but McGrath suggested it won't be a lengthy stay.

D'Angelo said the injury is common among seniors who fall and can be painful. He said a patient in his 90s would generally take three or four months to heal.

"It's a significant injury, but right now the president is in excellent shape, and we anticipate he'll make a full recovery," the doctor said.

He said Bush was "doing great" and "he's up and talking and out of bed."

A White House spokesman said President Barack Obama called Bush on Thursday morning to wish him a speedy recovery.

Bush, who has a form of Parkinson's disease and uses a motorized scooter or a wheelchair for mobility, has suffered other recent health setbacks. He was hospitalized in Houston in December for about a week for shortness of breath. He spent Christmas 2012 in intensive care at the same Houston hospital for a bronchitis-related cough and other issues.

The Republican served two terms as Ronald Reagan's vice president before being elected president in 1988. He served one term, highlighted by the success of the 1991 Gulf War in Kuwait, and then lost to Democrat Bill Clinton amid voters' concerns about the economy.

Bush was a naval aviator in World War II, and his torpedo plane was shot down over the Pacific. He also served as ambassador to the United Nations, envoy to China and CIA director.

He is the father of Republican former President George W. Bush. Another Bush son, Republican former Florida Gov. Jeb Bush, is running for president in 2016.

During the winter, Bush and his wife, Barbara Bush, live in Houston.