It was discovered outside Barnet Hospital, north London, shortly after 9am on 30 January. Officers believe that the box was left by a man, in his 30s, and urged him to come forward.
The Met Police said the foetus is believed to be around 16 weeks’ gestation, with a full-term pregnancy starting from 37 weeks. The matter is currently being treated as unexplained, and officers are urging the mother to come forward as there are concerns for her welfare.
Det Insp Matt Coad said: “At this moment, our priority is to ensure that the mother is OK and that she receives the appropriate medical attention. This is likely to be a traumatic time for her, and I would ask that she makes contact either with us, her local GP or a hospital.”
He added: “We believe that the box was left by a man, aged in 30s, who was wearing dark clothing. I would also encourage him to come forward so that we can help.”
Anyone with information is asked to call police via 101 quoting reference CAD 1599/30Jan.