What Preserved This Pregnant Egyptian Mummy’s Fetus for Millennia?

The combined effects of decomposition and embalming basically “pickled” the fetus, sealing it in its mother’s womb

Mummy on gurney going inside of a hospital scanner
Scientists examine the first-known pregnant Egyptian mummy. Warsaw Mummy Project

Scientists with the Warsaw Mummy Project have determined how the fetus of the world’s only known pregnant mummy was preserved. Thanks to the combined effects of decomposition and mummification, the ancient Egyptian fetus was essentially “pickled,” reports Science Alert’s Michelle Starr. The analysis is newly published in the Journal of Archaeological Science.

As the team explains in a blog post, corpses’ blood pH levels drop significantly over time, meaning the fetus would have been exposed to a highly acidic uterine environment that dissolved its bones. The salting process of mummification kept the mother’s bones from dissolving and almost “hermetically sealed” the uterus, preserving the fetus’ soft tissue inside the womb.

A similar process naturally preserved Europe’s famed “bog bodies,” whose pristinely preserved skin shrank in peat bogs’ high-acidity, low-oxygen environments. Sometimes, conditions in the bogs completely dissolved skeletons.

In the blog post, the researchers liken bone demineralization to soaking an egg in vinegar; placing the egg in an acidic environment for a few days makes the mineral components (the shell) dissolve, leaving the inside of the egg (the albumen and yolk) intact in a springy, ball-like state.

A black and white 3-D scan of the mummified fetus
A 3-D scan of the mummified fetus Warsaw Mummy Project

The team doesn’t know why the ancient Egyptians who mummified the woman left the fetus in her body but removed other internal organs (a common mummification practice). Lead author Wojciech Ejsmond tells CNN’s Lianne Kolirin that the fetus may have been too difficult to remove at its stage of development or was perhaps left in the womb for religious reasons. Regardless, experts believe the fetus’ presence could point toward the existence of more pregnant mummies.

Ejsmond finds it odd the fetus’ mother is the first pregnant mummy found by researchers.

In ancient Egypt, “[w]omen in reproductive age were maybe not constantly pregnant, but every few years they would have been pregnant,” he says to Insider’s Marianne Guenot.

The archaeologist posits that radiologists conducting body scans of other pregnant mummies simply missed the fetuses, which lacked bones and were therefore essentially invisible to X-ray scanners.

“Radiologists were looking for bones, and our case shows that, actually, you shouldn't,” Ejsmond tells Insider. “You should look for the soft tissue with a unique shape.”

Given the fetus’ position and the closed condition of the birth canal, researchers have determined the mother did not die in childbirth. A previous analysis found that the woman was between 20 and 30 when she died, and her pregnancy was between 26 and 30 weeks. Otherwise, little is known about the mummy, whom scientists have nicknamed the “Mysterious Lady.”

The University of Warsaw has owned the mummy since the early 19th century, wrote Szymon Zdziebłowski for state-run Polish news agency PAP in April 2021, when scientists first revealed the mummy’s pregnancy. The coffin’s inscription identified the mummy as a male priest named Hor-Djehuty, so the team taking an X-ray scan in 2016 was surprised to find a female body instead. Upon further inspection, the researchers spotted the little foot and hand of a fetus.

Egyptians are known to have reused coffins, so it’s possible the body was interred in Hor-Djehuty’s sarcophagus centuries ago. But archaeologists say the mummy shows signs of looting, including damaged wrappings around the neck, where plunderers might have snagged an amulet or a necklace. Illegal excavators or thieves may have partially unwrapped the Mysterious Lady for her jewels before placing her back in the wrong coffin.