She never regained consciousness and died eight days after the tragic accident having suffered asphyxia leading to brain damage.
"Her brain suffered irreversibly due to clamped arteries," said a local report.
Dmitry Ivanyuk, of the Belarus Investigative Committee, said: "The young woman was with her family at a friend's house in the village of Staroe Selo.
"On 31 August around 4.30pm her husband found her unconscious, with her neck jammed by the window of the front left door of their family car."
The mother was taken to Brest regional hospital "in a grave condition with signs of mechanical asphyxia and traumas", he said.
The investigative committee is examining the circumstances of the young woman's death.
The car was reported to be a BMW E34.
The couple had two children, Margarita, 4, and Arianna, 2.