The baby girl's body was found on Sunday afternoon in Großkugel. The 27-year-old mother apparently gave birth in her apartment that morning, and her partner discovered the body in the washing machine.
Police said the woman has since been hospitalized as their investigation continues.
Germany has been plagued with a spate of gruesome infanticide cases in the last few years that 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.