The newborn baby was discovered behind a family home beneath a hedge in the town of Namborn.
Authorities said they had been alerted to the possibility the child had been left alone by a hospital doctor who informed police that he had treated a 16-year-old girl with abdominal pain who had presumably recently given birth. He became concerned when the girl would not say what happened to the infant.
The tip led to a “dramatic deployment” that included helicopter searches for the baby, authorities said.
Police are waiting for an autopsy before they speak with the media later on Tuesday.
Gruesome cases of infanticide and child abandonment have haunted Germany in recent years.
The most notorious case involved a woman jailed for 15 years in 2006 for the manslaughter of eight babies. Sabine Hilschenz, a divorced, unemployed and alcoholic dental assistant from a depressed area of eastern Germany, hid the corpses in buckets, flowerpots and an old fish tank at her parents' home.
In October, the remains of four babies were found in a Berlin apartment following the suicide of their alleged mother. Later the same month a man's dog found a dead infant along Munich's Isar River bank.