Police have arrested four people suspected of offering illegal gender tests to women from the backseat of a car in Xiamen, Fujian province, Xiamen’s Bureau of Public Security confirmed on Tuesday.

In May, a woman reported to the family planning authorities of Xiang’an district that she had received a fetus gender test from a gang in a private car.

The woman called the test providers “cheats and murderers” as they said she was carrying a girl but after she had an abortion the following day, she learned the fetus was male, police said.

After receiving similar tip-offs, the family planning authorities informed the local police, who then began a month-long investigation and busted the group on July 5.

The group included a leader, a middleman, a driver and another man who stood watch to ensure nobody approached the car.

The police investigation found that since the end of last year, the group has been operating all around Xiamen with an ultrasound machine in the back of a car.

More than 40 women have paid for the gender tests and eight women had abortions after learning they were carrying female fetuses.

The procedure took only a few minutes and each pregnant woman paid 600 yuan ($97) for the service.

If the gender of the fetus was male, the group charged the pregnant woman an extra 200 yuan.

A police officer surnamed Wang who was involved in the investigation said the group operated in a very crafty fashion.

The group leader, surnamed Li, would not tell clients the exact whereabouts of the car but instead had the man whose job it was to stand watch lead the women to the vehicle, Wang said.

Li also required that the clients not be accompanied by any relatives, Wang said.

It is illegal in China for medical institutions or individuals to determine the sex of a fetus unless it is medically necessary as the practice tends to encourage parents with a traditional preference for sons to abort female fetuses.

Since the 1980s, China’s sex ratio at birth has increasingly skewed toward men. Data from the National Bureau of Statistics show that China’s ratio of males to females at birth was 117.7 to 100 in 2012.

“Illegal ultrasound fetus gender testing poses a serious danger to women’s health as most pregnant women seeking the service have traditional preferences for male children and will choose to abort after learning they are carrying baby girls,” said Gan Mantang, a sociologist at Fuzhou University.

“To make it worse, the illegal gender testing that causes a gender imbalance will give rise to social instability in the future as more and more men will stay single. Thus, the practice should be harshly punished,” Gan said.

sunli@chinadaily.com.cn