In a 1,300-year-old grave lies the skeletal remains of a young woman with a hole in her head and a fetus between her thighs. All signs point to a normal, proper burial – she’s face up in a brick grave – and it initially had researchers stumped. Now, eight years after finding the remains in Bologna, Italy, scientists believe they have a bizarre explanation.

The woman was between 25 and 35 when she died, according to scientists at the University of Ferrara and the University of Bologna. Using the length of the fetus’ femur, researchers estimate the fetus was around 38 weeks, which means the woman was close to her full 40-week term when they died.

The fetus appears to have been partially emerged from the woman’s vaginal cavity much like we see in a live natural birth, but the head and torso of the fetus were found between the thighs while its legs were still in her pelvic cavity. While it looks as if the pregnant corpse had given birth, researchers say this is consistent with a phenomenon called post-mortem fetal extrusion, or “coffin birth”.

The rare event occurs when a dead fetus is expulsed from a pregnant woman’s body after her and her unborn child’s deaths. It’s thought that gases generated during the body’s decomposition caused the fetus to emerge – even rupture – through the vaginal walls.

The hole in her head has an equally rational – albeit gruesome – explanation. Drilled in the center of the woman’s skull, it was probably from a medieval medical treatment called trepanation used to treat a variety of ailments. Dating back thousands of years, the technique was thought to relieve pressure in the skull. The hole was likely caused by a circular cutting tool. Three parallel horizontal grooves are similar to those observed in other cases, say the researchers. The bone showed signs of healing, indicating she could have been alive for at least a week afterwards.

Unfortunately, it was probably this procedure that was meant to save her life that ultimately caused her death. Because trepanation was once used to treat hypertension, it was probably meant to treat a hypertensive pregnancy disorder like preeclampsia. 

"Some of the most common manifestations of this disease are high fever, convulsions, consistent frontal and occipital cephalalgia, high intracranial pressure, cerebral hemorrhage. All these symptoms, from prehistory to the 20th century, used to be treated with trepanation," say the authors in their study, published in World Neurosurgery.

In spite of the intervention – or perhaps because of it – the woman did not survive and died with the fetus still in her womb.