The exact cause of the infant's death will be determined in the coming days after the autopsy analysis is finished, the public prosecutor's office in Dresden said on Monday.
The infant's 20-year-old mother was arrested on Saturday and remains in police custody under suspicion of manslaughter. Her grandparents, with whom she lives, discovered the child concealed in a duffel bag in their cellar. According to preliminary investigation, no one in the mother's social circle was aware of her pregnancy.
Four dead infants have been discovered in the German state of Saxony so far this year.
Germany has been plagued with a spate of gruesome infanticide cases in the last few years which have shocked the country. One woman who killed nine of her babies was sentenced to 15 years in prison in early April.
In May, a 44-year-old woman was arrested when her family found three dead babies in her freezer near Bonn.