Prosecutors last week requested Nadezhda Buyanova, 68, be jailed for six years for spreading "fakes" about the Russian army.
More than 1000 people have been criminally prosecuted in Russia for speaking out against the war, according to rights project OVD-Info, while about 20,000 have been detained for protesting.
Buyanova's case is part of a wider trend in Russia of people denouncing each other for alleged political crimes.
OVD-Info has recorded 21 such criminal prosecutions in the more than two and a half years since the start of the conflict.
Eva Levenberg, a lawyer for the rights group, told Reuters a further 175 people had faced lower-level administrative cases for "discrediting" the Russian army as a consequence of people informing on them, and 79 of these had been fined.
Reuters has requested comment from the Russian Justice Ministry about the OVD-Info data and the use of denunciations to support prosecutions, including Buyanova's.
The case against her was personally launched in February by the head of Russia's Investigative Committee, which handles serious crimes.
It was prompted by a complaint from a mother of a seven-year-old boy who had taken him to see Buyanova at her clinic.
The boy's father, from whom the woman was divorced, had been killed while fighting for Russia in Ukraine.
The woman, Anastasia Akinshina, recorded a video in which she said that Buyanova had referred to her child's father as a "legitimate target of Ukraine".
The video was posted by Mash, a Telegram channel with about 3 million subscribers.
Buyanova denied making the statements.
She was placed in pre-trial detention in April.
A group of Russian doctors wrote an open letter in Buyanova's defence, calling the denunciation a "disgrace".
A petition for her release has garnered more than 6000 signatures.
