A body was discovered by staff at the Bell Waste Control Site in Scunthorpe, the man who made the discovery is said to be “very distressed”.
The baby is said to have been under six months in age.
A police spokesman said: “”At this time, very little is known in terms of the circumstances which led to the baby seemingly being discarded.
“We are concerned that the baby’s parents, in particular the mother, may need help and support following the loss of her child and as such she may be very vulnerable at this time.
“We are urging anyone who can help identify the parents of this baby or the parents themselves to come forward in order for us to make sure they get any support or medical treatment that may be required.”