After video footage of the dead rat in the woman's soup circulated on social media, the chain's shares dropped by 12%, losing £145m in value to reach its lowest level since October a year ago, before regaining value.
The restaurant allegedly later offered Ma 5,000 yuan ($728) in compensation for the incident - a price he was willing to negotiate after the hospital visit, he told the South China Morning Post.
Weifang.sdnews.com reported that a customer at an Xiabu Xiabu outlet based in Weifang city in the Shandong province found a dead rat in a hotpot meal on 6 September. As of Wednesday, the hotpot restaurant's market value is slowly recovering.
Mr Ma, her husband, said he informed the restaurant staff to the situation and was offered cash for abortion if they were anxious about the health of the baby.
Mr Ma also alleged that one of the staff had suggested his wife get an abortion if she was anxious about the baby's health, and offered him 20,000 yuan for the procedure. "I'm never going to eat hotpot outside again", said one user.More news: Seattle Storm sweeps Washington Mystics
By the close of trading on Tuesday, shares in the chain's parent company, Xiabuxiabu Catering Management, had fallen almost 12.5 per cent, at one point dropping to their lowest in nearly a year.
"Xiabu Xiabu has always been one of my favourite restaurants, I thought they were quite clean as well..."
Another user asked: "If something happens to her baby, how are they going to compensate her? Is a life worth only 20,000 yuan?" It's a fun, sociable meal popular across China - a country with much regional variation in cuisine - and chains are cropping up alongside mom-and-pop stalls.
Xiabu Xiabu has since issued a statement saying food safety was a high priority for staff and the chain would make whatever improvements were deemed necessary.
The chain, which is known for its "hot pot" - a dish which involves diners cooking their own vegetables and other ingredients in a large bowl of simmering broth - took a hit after the footage emerged last week.