Contractors were working to fix a clogged toilet Monday in the 800 block of East Russell Street when they found the 3- to 4-month-old fetus, NBC-TV, Philadelphia, reported.
"It may not be a crime scene," Chief Inspector Scott Small said. "We're still going to look into how developed the child was. But at this point it appears that someone may have had a miscarriage."
Police spoke with a couple in their 60s who live in the home, which had a "for rent" sign outside, and said it is possible the couple rented a room to a pregnant woman.
An autopsy was performed to determine the cause of death.