By Diane Mapes

While a 92-year-old woman delivering a 60-year-old baby may sound like a bizarre plot twist from the movie “Benjamin Button,” it’s true. Huang Yijun, 92, of southern China, recently delivered a child which she’d been carrying for well over half a century.

The baby wasn’t alive, however. The woman was carrying a lithopedion — or stone baby. It's a rare phenomenon that occurs when a pregnancy fails and the fetus calcifies while still in the mother’s body.

According to Dr. Natalie Burger, endocrinologist and fertility specialist at Texas Fertility Center, lithopedions start off as ectopic pregnancies, a condition where the fertilized egg gets stuck on its way to the womb, implants and develops outside the uterus.

“Usually an ectopic pregnancy will mean a [fallopian] tubal pregnancy, but in a small percentage of cases, the pregnancy can actually occur in the abdominal cavity — in places like the bowel, the ovary, or even on the aorta,” she says. “These are very rare locations and they can be very dangerous.”

In most cases, Burger says, doctors will recommend the pregnancy be terminated due to the extreme risk to the mother. Or the fetus will simply die on its own due to a lack of blood supply.

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“The vast majority never get anywhere close to multiple months of pregnancy,” she says. “They die, the tissue breaks down and they’re gone.”

In certain cases, however, the implanted fetus gets to an advanced stage before it dies. Too large to be absorbed by the body, the remains of the child or its surrounding amniotic sac slowly calcify, turning to stone as a way to protect the woman’s body from infection from the decomposing tissue. Because the mother’s body doesn’t recognize the hardening mass as foreign, if there are no other complications she can basically just go on with her life.

Stone babies are extremely rare, but you wouldn’t know it considering how often they’ve been used as a plot device in novels, short stories and TV shows. For example, in recent years, they’ve shown up on “Law & Order: Criminal Intent,” “Nip/Tuck” and the Australian series, “All Saints.” Maybe calcified babies are so popular because they tap into a mythological fascination with or deep fear of a soft, innocent body turning to stone.

According to a 1996 paper in the Journal of the Royal Society of Medicine, only 290 cases of lithopedion have ever been documented by medical literature, the earliest being that of a 68-year-old French woman Madame Colombe Chatri who, when autopsied after her death in 1582, was found to be carrying a fully-developed stone baby in her abdominal cavity. Chatri, whose abdomen was said to be “swollen, hard and painful throughout her life,” had been carrying her stone child for 28 years.

The mean duration of a “stone pregnancy,” according to the Journal article, is 22 years. Some women, such as China’s Huang Yijun, have carried their calcified fetuses for more than 50 years.

How could a woman walk around with a stone baby for years and years and not realize something was amiss?

“In some cases, there would be symptoms of an early pregnancy and then they would go away,” says Burger. “The women would just think they just lost a pregnancy and wouldn’t think any more of it.”

In other cases, a lack of money or medical resources comes into play. Huang Yijun told reporters she didn’t have the money to have her fetus removed after doctors told her it had died inside her in 1948. So, she simply “did nothing and ignored it.”

Other women, particularly those living in countries where obstetric care isn’t readily available, are unaware of their condition until the calcified mass causes a serious health issue. According to Burger, lithopedions — which can weigh up to nine pounds in the case of a full-grown fetus — have been known to cause intestinal obstruction, pelvic abscess, problems with delivery in future pregnancy and fertility issues, among other things.

They’ve also been known to cause quite the public sensation.

In 1582, the autopsy findings of Madame Chatri – complete with illustrations depicting the woman and her stone child — became an instant medical bestseller and the calcified fetus was quickly sold to a wealthy French merchant (sort of the P.T. Barnum of his day) who put it on display at his museum of curiosities in Paris. The fossilized fetus reportedly changed hands several times after that, finally ending up in the King of Denmark’s royal museum in 1653. Two hundred years later, the museum was dissolved and the stone fetus was transferred to the Danish Museum of Natural History.

Several years after that, the stone baby was lost. Or perhaps laid to rest, at long last.