Some local residents yesterday saw the woman, Latabai Narayan Gawli, banging her infant daughter against an electric pole near a railway track on the outskirts of the Jalgaon railway station.
Seeing the people rushing towards her, Latabai threw the injured baby aside and jumped on the railway track where a train was speeding towards Bhusawal.
While the baby died on the spot, the woman was declared dead after she was rushed to the civil hospital.
Latabai's brother later filed a police complaint against her 52-year-old mother-in-law of mentally and physically torturing his sister, based on which she was detained and charged under sections 306 (abetment to suicide) and 498 (cruelty) of IPC.
Further investigation was on, police added.