"She has not broken anything," said spokeswoman Joanne Drake. "We don't have anything beyond that."
Reagan's doctor recommended hospitalization as a precaution after the tumble Sunday and she was admitted while awaiting results of several tests, the Los Angeles Times reported Monday.
Reagan, 86, was in the same room at St. John's Health Center in Santa Monica where her husband, former U.S. President Ronald Reagan, recuperated from a hip fracture years ago, the Times said.
She cared for the former president while he suffered from Alzheimer's disease until his death in 2004. She works at the Ronald Reagan Presidential Library in Simi Valley.