Police are investigating the discovery of a foetus in Christchurch's wastewater treatment plant at Bromley.
It is likely the foetus entered the Bromley plant four to six hours before it was discovered yesterday morning, police say.
A spokesperson said it was is likely the mother had been in the mid-term of her pregnancy, estimated between 20 to 30 weeks.
There were no indications at this stage that anything suspicious has occurred but police are concerned the woman may need medical assistance.
Police hope to identify her and confirm she has received the care she may need.
The treatment plant processes sewage from 100 pumping stations across the city.