Tara Devi, who was three months pregnant, was allegedly beaten up by Jharkhand Vikas Morcha (Prajatantrik) legislator Chandrika Mahta at her Khajatola village home in Giridih district two days ago over a land dispute.
The woman suffered a miscarriage following the incident, the FIR lodged by the woman said.
Superintendent of Police A B Homkar said an FIR has been lodged against Mahta in this regard.
Peeved at not finding her husband at home, the legislator had allegedly beaten up the woman, the FIR said.
The accused legislator could not be contacted for comments.
However, JVM's leader in the assembly Prdip Yadav claimed Mahta was not present when the incident occurred and demanded an impartial inquiry.
He said the incident was being politicised.