The incident came into light when the 19-year-old girl's body was fished out of the canal on Tuesday, Hastinapur police station in-charge P K Singh said.
The victim was allegedly having an affair with a youth from the same village. Her parents got to know about it when one day she was unwell and they took her to a doctor, who said that she was eight-months pregnant.
The post mortem report confirmed that the girl was strangulated following which a case of murder has been registered against the three accused.
The girl's family members are absconding since the incident. Efforts are on to nab the accused, he added.