The victim Ratna, who was later admitted to a hospital, gave birth to a still-born girl, they said.
The incident took place Saturday when Ratna's two-year-old son had a minor fight with a three-year-old Amit from the neighbourhood.
"During the fight, Amit called his uncles, the accused Deepu, Kamal and Deepak who then started kicking and punching Ratna," said a police spokesperson.
"Soon Ratna started bleeding. She was admitted to a hospital by her relatives where she gave birth to a still-born girl," he added.
A case has been filed against the accused and the matter is being investigated, police said.