Just this November, his daughter underwent seven hours of surgery to repair a slipped disk in her vertebrae.
Berenson's story began in 1995, when she was arrested at the age of 26 on suspicion of aiding leftist rebels.
She was sentenced at first to life imprisonment, but a civilian court retried her in 2000 and convicted her of a lesser crime of terrorist collaboration and reduced her sentence. All along, she has denied any wrongdoing.
In prison, she met Anibal Apari, now a lawyer and former member of the Tupac Amaru Revolutionary Movement, which was best known for its four-month takeover of the Japanese ambassador's residence in 1996 in Lima.
Berenson married Apari in 2003 when he was released from prison and gave birth to his son, Salvador, in November and is raising him as a "single mom," according to her father.
Berenson was up for parole in November of this year, but a new antiterrorist law was enacted in October, eliminating parole for all such crimes.
Whether their daughter will get out as planned is "an open question right now," said Rhoda Berenson. "We are still appealing it."
More likely, Berenson will serve her full sentence until 2015, when she will be expelled from Peru. By law, her son, who has dual U.S.-Peruvian citizenship, is only permitted to remain with her in prison until he is 3.
Mark Berenson said he and his wife would take custody of Salvador if their daughter is not released before then.
"One of the really sad things is that when she had the baby it was with the expectation of her being on parole," said her mother. "But if there is no parole, she is going to have to relinquish the baby."
Rhoda and Mark Berenson have made numerous trips to Peru -- about six a year over the last 14 years -- to visit their daughter in a variety of prisons. They were with her in Lima for the birth of their grandson May 6 and again before Thanksgiving for her spinal surgery.
"It was really horrible in the beginning, but it has improved for Lori and all the prisoners," said Rhoda Berenson. "We can spend all day together with no screens between you."
The concrete prison where she now lives in Lima has few amenities. Water comes only once a day and prisoners store it for personal use. There are no regular toilets.
"She does a lot of squatting and is exposed to the elements, but it's not that cold," said her mother.
But her parents see a happier daughter emerging. She does handicraft work in prison and looks after Salvador, though with her back injury, she needs help lifting her son.
"The baby has had a huge effect on her in a very positive way," said Rhoda Berenson. "In 14 horrible years, something really wonderful came of it. Giving birth to Salvador meant that in spite of the Peruvian government's attempts to ruin her life, they didn't deprive her of motherhood."
Lori Berenson still wants to help others and even though it's too late to become a doctor, she mentions to her mother than she would like to do something "medically related" when she gets out of prison.
"She is still more interested in helping people than becoming rich," said Rhoda Berenson. "Those things haven't changed."