Over the past two years, the color-coded system has been expanded to Beijing as well as Shandong, Jiangxi and Guizhou provinces.

Lin Ge, a doctor at the Wudang District Maternity and Child Health Hospital in Guiyang, the capital of Guizhou province, said pregnant women assessed as a red or purple risk are transferred from town-level hospitals to bigger, better-equipped ones for regular health checks throughout their pregnancies.

"Such a management method ensures one-on-one medical care for all the pregnant women and guarantees the safety of mothers and children as much as possible," he said.

In addition, Shanghai has expanded its medical health service in the past decade to nearly 5,300 health institutions scattered across 15 districts.

At least one 3A-grade hospital, the highest of China's three-tier grading system for hospitals, is available in each of Shanghai's suburban districts.

"Shanghai has become a medical high-water mark for the country, and the region is attracting the largest number of patients from other provinces," said Wu Jinglei, director of the Shanghai Health Commission.

"Shanghai's ability to serve the Yangtze River Delta region and the whole country medically has improved continuously."

Shanghai was also the first region on the mainland to include free urinalysis checks to screen for kidney diseases.

The health check has been compulsory for primary and junior middle school students since 2003.

Since 2010, the screening program has been expanded to 11 provincial-level regions, covering more than 300,000 students.

Xu Hong, Party chief of the Children's Hospital of Fudan University who initiated the screening program, said kidney disease has become a global public health issue. Urinalysis can help identify child patients, who are asymptomatic but may develop kidney problems, Xu said.

Zhi Yuan contributed to this story.