Beijing (CNN) -- Like many mothers, Yan breastfeeds her child. But she's also found a way of making it pay.
After noticing she produces more than she needs, Yan -- who lives with her five-month-old baby in Shenyang, the capital of China's northern Liaoning Province -- decided to sell it.
"I don't want to waste my milk," she told CNN. "I heard that others sell breast milk online, and I thought 'Why not sell mine?' I created a Web page and started my business."
A cursory search for "breast milk" on 58.com, a Chinese online shopping platform, reveals no shortage of mothers offering to sell their breast milk. From Shanghai to Guangzhou, nursing mothers are cashing in on this booming online trade.
"I just need to wait for calls," said Yan. "I provide fresh and frozen breast milk. But you have to pick it up yourself."
According to Yan, the market price is around 5,000 RMB (US$814) for a month's supply. In contrast, a month's worth of conventional baby formula costs around 2,000 RMB (US$325) in China.
After China's tainted milk powder scandal in 2008, many new mothers who were unable to produce enough breast milk for their infant resorted to buying formula overseas — most notably in Hong Kong.
However, earlier this year Hong Kong introduced limits on the amount of milk powder travelers can take out of the territory, over concerns about shortages and a "black market" in formula sold at vastly inflated prices.
The restrictions have encouraged new mothers to find other means of sourcing milk to feed their babies.
"If I don't have enough breast milk I would prefer to purchase human breast milk, because I don't trust our milk powder," explained Fang Lu, a newlywed who is planning to start a family.
This week, the mistrust of milk powder extended to the biggest single supplier of dairy products to China.
On Saturday, New Zealand company Fonterra announced that a strain of bacteria that causes botulism had been found in batches of an ingredient used to make baby formula, as well as sports drinks.
China immediately halted imports of Fonterra-produced Whey Powder and Dairy Base powder, and increased inspections of New Zealand dairy products.
Some mothers may be turning to others' breast milk as an "safer" alternative but health experts say it doesn't come without risks.
According to the U.S. Food and Drug Administration, babies fed unscreened milk from other mothers could be exposed to infectious diseases, including HIV, and illegal and prescription drugs.
It adds that, if not stored properly human milk, "like any type of any type of milk, becomes contaminated and unsafe to drink."
In May, China opened its first breast milk bank at the Guangzhou Maternity and Childcare Hospital and just last week another opened in Nanjing, Jiangsu province.
However, like others around the world, they impose strict controls on who is able to donate, limiting the availability of supply.
The trend of mothers' buying human milk online is not limited to China. A number of sites exist online to match buyers and sellers.
Separately, an increasing number of women are turning to informal milk sharing sites that trust donors to properly store their milk and declare any lifestyle or health risks to prospective recipients. On those sites, the sale of breast milk is strictly prohibited.
In China, trading human breast milk online occupies a legal gray area. While the Ministry of Health Law Supervisor Department has declared that human breast milk cannot be a commodity, no laws regulate or explicitly prohibit its sale.
But while the practice may not be encountering legal obstacles, some people spoken to by CNN expressed discomfort with the growing popularity of the trade.
Wangyan Liu, a doctor from Beijing, said he was concerned about breast milk sales, saying that poorly stored milk could make infants sick.
"If conditions of breast milk storage are not good, then it's more dangerous," he said. "We need laws for the breast milk business."
But for Yan, the emergence of China's breast milk market is a positive development -- and not one that is solely motivated by profit. "I think the business is totally fine. I have excess breast milk and I want to help others -- and earn some money," she said.