Feng Jiamei, from Zhenping county in Shaanxi, was allegedly made to undergo the procedure by local officials in the seventh month of pregnancy.
Ms Feng was forced into the abortion as she couldn't pay the fine for having a second child, US-based activists said.
Rights groups say China's one-child policy has meant women being coerced into abortions, which Beijing denies.
National and local family planning authorities are investigating the incident, the Global Times newspaper reports.
"Feng Jianmei's story demonstrates how the One-Child Policy continues to sanction violence against women every day," said Chai Ling of the US-based activist group All Girls Allowed.
The group says it spoke to Ms Feng and her husband Deng Jiyuan after the incident. Mr Deng said his wife had been forcibly taken to hospital and restrained before the procedure.
Unnamed local officials in Zhenping county quoted in local media reports denied forcing Ms Feng to have the abortion.
"This is what they say the Japanese devils and Nazis did. But it's happening in reality and it is by no means the only case... They [the officials] should be executed," one reader on news website netease.com said, according to Agence France-Presse.
Activist Chen Guangcheng, who was put under virtual house arrest for campaigning against forced abortions, fled China to the US last month.