Huang Yijun, the Chinese woman who had been carrying a stone baby for nearly 60 years.

Huang Yijun, the Chinese woman who had been carrying a stone baby for nearly 60 years.

According to media reports Monday, when a 92-year-old Chilean woman was taken to the hospital after a fall, doctors performed a routine exam and were shocked when a hip X-ray revealed a 4.4-pound fetus filling her abdominal cavity.

According to Yahoo Health, hospital director Margo Vargas Lazo tells the BBC that the calcified fetus was “large and developed,” and had probably been there at least 50 years.

The AFP adds that the woman wasn’t experiencing any pain because of it, and notes that the fetus was roughly seven months along when it died.

The condition is called “lithopedion,” and happens when a fetus dies and calcifies outside of the womb. Lazo tells the Efes news agency in Chile that this case is “extraordinarily rare,” reports the Independent.

Given her age, doctors sent her home a few hours later without performing an operation to remove it, so she’ll likely leave the world with her unborn baby inside her.

A study published in 2000 in the Sao Paulo Medical Journaldefined just how rare: the phenomenon happens in just 1.5% to 1.8% of the abdominal pregnancies that occur—and the incidence of those are 1 in 11,000.

“There have been less than 300 cases in 400 years of world medical literature,” per the study.

It looked at those recorded cases and found that two-thirds of the diagnoses happened in women over 40, with the “period of fetus retention” ranging from four to 60 years. As with other cases, the Chilean woman was unaware of the presence of the fetus.

The first reported case of lithopedion was Madame Colombe Chatri, a 68-year-old French woman, reports the Daily Mail.

An autopsy after her death in 1582 revealed she had been carrying a fully-developed stone baby in her abdominal cavity for 28 years.