Over the weekend, security researcher Victor Gevers stumbled upon a Chinese database of 1.8 million women that listed their names, physical addresses, phone numbers and one potentially more troubling status: whether they were “breed ready.” Anyone with the IP address could visit the database, said Gevers, who had previously uncovered a database of 300 million leaked Chinese private messages last week and works for the Dutch nonprofit GDI Foundation.

“We don’t know who is behind this database and what the intention was...that is the part that worries us the most,” Gevers told The Verge. He says the database’s IP address was in China and that most of the women included in the records were located in Beijing.

The database remained online for only one and a half days after Gevers reported it on Twitter, he says, and closed down by 4AM ET on Monday. The database had contained information about each woman’s education and marital status as well. There was also evidence that more details about the women were being tracked — the dataset included fields for “Political” and “Has Video,” and some linked to women’s Facebook profile pages. Facebook remains banned in China, so women who had Facebook pages must have accessed the platform through a VPN or by traveling overseas.

In China, they have a shortage of women. So an organization started to build a database to start registering over 1,8 million women with all kinds of details like phone numbers, addresses, education, location, ID number, marital status, and a ”BreedReady" status? pic.twitter.com/fbRKsbNHPJ — Victor Gevers (@0xDUDE) March 9, 2019

The “BreedReady” data point seems to be binary, so each woman’s dataset would say either 1 to indicate yes or 0 to indicate no. Almost 90 percent of the women were listed as single. The women in the database ranged in age, from 15 to 95, but “BreedReady” women were clearly a subset: the youngest with the BreedReady status was 18 years old and the oldest with the status was 39.

While it’s a complete mystery what the database is being used for, some internet users suggested it could have been part of a government effort to keep track of fertile women as China’s birth rates dip to a historic low. In January, China’s National Statistics Bureau reported no more than 15 million children were born in 2018, a two million dip from the year before. Users on Chinese social media reacted to the database leak by comparing it to the Hulu series’ The Handmaid’s Tale, a dystopian story where fertile women are considered valuable cattle and even bartered for as resources. (One of those comments has since been censored.) Still others suggest it could be far more innocuous — perhaps it was just data from a Chinese dating app.

As to how people could avoid being listed on this database and keep their data secure, Gevers had the following thoughts: