The discovery was made at a sprawling gravel quarry west of the village of Thorney, which is about eight miles east of Peterborough.
The researchers say the find, coming just two months after the discovery of well preserved remains of a Bronze Age man 50 metres away, points to the existence of an ancient cemetery.
According to a report in the local Peterborough Today, experts from the Phoenix Consulting Archaeology discovered the baby - which was under a year old, or possibly a stillborn - during routine excavation work.
The child was lying in a grave lined with birch bark, and a complete pottery vessel, with an offering of grain or wheat inside, found next to the bones.
Lead archaeologist Dr Andy Richmond said: "We knew about the existence of round barrows because aerial shots detailed crop growth variations. But over the years, these mounds have been ploughed away, disturbing the burial grounds".
"To find the skeleton of such a young child was an exciting discovery, and the bones were extremely soft," he said.
John Penny, a senior surveyor for Bardon Aggregates, which runs the quarry, added: "Excavation work at the site has been ongoing for eight years and, until now, little has come to light regarding the men and women who lived in the area".
"However, in recent months the archaeologists have come across remarkable evidence that points to the lives and routines of people who carved out an agricultural landscape in the area, in the form of a communal burial ground," he said.
He said the excavations would, nevertheless, help historians and archaeologists piece together the jigsaw of life on the edge of the Fens from the late Neolithic period through to the late Bronze Age.
As of now, the skeletons and artefacts will be sent for testing to gauge a better understanding of the social side of their ancient communities, and to determine age, sex, diet, disease and dental information.
The will eventually be displayed at Peterborough Museum and Art Gallery, in Priestgate.
After archaeologists are satisfied that all potential Bronze Age findings have been removed, Peterborough City Council will sanction the quarrying of the burial site, the paper said