The medical examiner on Monday identified the girl as 5-month-old Mikayla Rainwater.
According to the medical examiner's report, the baby's mother said that she fed her daughter about 11 a.m. before laying the girl on a queen-sized bed with the child lying on her back.
The child's father told Milwaukee police that the baby had slept with them in the adult bed all night.
The Milwaukee Journal Sentinel reports no trauma was found on the infant. The cause of death has not yet been determined, pending further toxicology tests.