Researchers found the bones of a fetus along with the woman’s remains in the brick coffin.
They say the baby was a coffin birth or a rare occurrence when the gases that build up during decomposition expel the baby.
Researchers say to find both the coffin birth and the trepanation, especially trepanation during the European early middle ages, in one person's remains is extremely rare, CNN reported.
The study concerning the woman's remains, which were discovered in 2010, was recently published in the journal for World Neurology.
Doctors don't know why she had the brain procedure, but speculate that she may have had pre-eclampsia or eclampsia, and that it was used to relieve pressure she had in her head. Bone healing around the hole in her skull shows that she lived about a week after she had the procedure, CNN reported.
The woman, doctors said, was in good health, but she may have had an illness that wouldn't be reflected in her skeleton. They also are not sure if the baby would have been able to be born alive, but it was late in the pregnancy, as the baby was about 38 weeks, CNN reported.