Officers were searching yesterday for the newborn baby after finding 23-year-old Darlene Haynes dead in her apartment in Worcester, Massachusetts.
Ms Haynes was about eight months pregnant at the time of her murder. Authorities said her child, if alive, would need urgent medical attention.
The woman’s body was discovered by her landlord William Thompson responding to what he described to a local news station as a “horrifying smell”.
On entering the tenant’s bedroom he found her body wrapped in bedding and stored in a closet.
Authorities believed Ms Haynes may have been dead for several days and she had not contacted friends or family members since last Thursday.
The exact cause of death has not been determined but an autopsy revealed Ms Haynes had received head injuries.
Her one-year-old daughter is staying with relatives, police said.
Officers have interviewed the child’s father, Roberto Rodriguez.
No arrests have been made.