WUFU, China — After their daughter was born, Bi Kaiwei and his wife, Meilin, decided to adhere to China's one-child policy and its slogan, "Have fewer kids, live better lives."

For them and other couples who lost an only child in this week's massive earthquake, the tragedy has been doubly cruel. Robbed of their sole progeny and a hope for the future, they find it even harder to restart their shattered lives, haunted by added guilt, regret and gnawing loss.

"She died before becoming even a young adult," said Bi, an intense, wiry chemical plant worker, standing beside the grave of 13-year-old Yuexing — one of dozens sprinkled amid fields of ripened spring wheat and newly planted rice. "She never really knew what life was like."

Yuexing, a bright sixth-grader, was in school when Monday's quake struck, bringing the Fuxin No. 2 Primary School crashing down, killing her and 200 other students. Teachers had locked all but one of the school's doors during break time, parents said, leaving only a single door to escape through.

Many among the more than 22,000 people killed across central China were students in school. Nearly 6,900 classrooms collapsed, government officials said Friday, in an admission that highlighted a chronically underfunded education system especially in small towns and compounded the anger of many Chinese over the quake.

In Wufu, a farming village two hours north of the Sichuan provincial capital of Chengdu, most of the dead students were a couple's only child — born under a policy launched in the late 1970s to limit many families to one offspring. The policy was meant to rein in China's exploding population and ensure better education and health care.

The "one-child policy" has been contentious inside China as well as out. The government says it has prevented an additional 400 million births. But critics say it has also led to forced abortions, sterilizations and a dangerously imbalanced sex ratio as local authorities pursue sometimes severe birth quotas set by Beijing and families abort girls out of a traditional preference for male heirs. The policy is law but there are exceptions.

Resistance by ordinary Chinese has forced Beijing to relax the policies, allowing many rural families to have a second child if the first was a girl. But in Wufu, the family planning committee seems to have prevailed on most families to stop at one child. Slogans daubed on boundary walls and houses all along the rutted country road leading to Wufu call on families to "stabilize family planning and create a brighter future."

Standing in the rubble of the school holding his daughter's ID and a posed shot taken at a local salon, Bi — pronounced "Bee" — said starting a new family, either by having another child or adoption, is simply imponderable.

"I'm 37 years old and my child was 13. If we were to do it again, I'd be 50 when this stage comes along," Bi said.

Parents who lose children in disasters often feel intense guilt for what they see as a failure to protect them, said psychology professor Shi Zhanbiao. Parents, he said, may also recall their past relationships with their children with regret, thinking they were too stern, did not show them sufficient love or did not interact with them enough.

"They'll think that if they just hadn't sent their children to school that day, they would have been saved," said Shi, a researcher with the Chinese Academy of Science in Beijing.

The loss is intensified for those with no other offspring to lavish with care and affection, Shi said. And in China, other, more practical concerns may also come into play because children are generally expected to care for their aging parents.

"They'll be worried about the future, because for the later part of their lives, they'll have no one to depend on," Shi said.

Parents in Wufu said they plan to bring a formal complaint over what they say was corruption and malfeasance in construction of the school. They say officials moved the students from a group of one-story classrooms — all of which survived the quake — into a modern-looking, but unsafe building.