Netcare 911 paramedics discovered a male foetus on Tuesday around noon at a sewerage plant in Vanderbijlpark, south of Johannesburg.
Netcare 911 spokesperson Nick Dollman said paramedics were flagged down by a police vehicle and asked for assistance.
"The crews went to the sewerage works and assessed a well-developed male foetus. Tragically there was nothing that the crew could do to help as there were no signs of life," Dollman said.
"Documentation pertaining to the death was completed by Netcare 911 and handed over to the police."
He said police were on the scene and investigating the incident.