"It was by the grace of God. A nurse who was responsible for my sister's operation allowed me to take my nephew away," said the boy's uncle, Terry Gao, who moved to Hong Kong last year. "I just ran as fast as I could after taking the baby from the pail. He is a rare lucky one among thousands of cases of induced labour and abortion that occurred every year in my hometown."

He Shaoying was caught by local officials in neighbouring Shishi when she was eight months' pregnant with her second child 20 years ago.

"I was told it was a boy after the induced labour was over," she said. "I remember him crying as soon as he was pushed from my body. But soon afterwards, the medical staff said he had died. Some of my friends working in the hospital said my boy was given an injection that killed him."

Now a 55-year-old kindergarten teacher, she said she had suffered mental problems after her loss, but had felt better recently as she was due to become a grandmother in July.

Besides forced abortions and induced labour, contraceptive operations have also harmed a great many women since the one-child policy was introduced.

The Ministry of Health says more than 286 million women were fitted with birth-control devices between 1980 and 2009. Investigations by birth control experts have found that many suffered from various side effects.

Former family planning minister Zhang Weiqing told a video conference in 2007 that medical complications were common because a third of the 150,000 medical staff responsible for birth control operations lacked professional qualifications.

Professor Ai Xiaoming , a specialist in women's and children's welfare at Guangzhou's Sun Yat-sen University, is one of many victims of botched birth-control operations. Like millions of women who were forced to use a contraceptive intra-uterine device (IUD) after delivering their first child, Ai did not realise that the minor operation would lead to a hysterectomy.

Ai said she was ordered have an IUD fitted in 1982, when she was 29 and had just delivered her first child.

"Local birth-control officials just ordered me to have the contraceptive operation, but there were no regular check-ups afterwards," she said. Ai had a hysterectomy in 2002 after contracting a serious infection.

"Even I, a well-educated woman with a PhD, couldn't find any women's health information channels telling us how to protect ourselves," Ai said.

Dr Kun Ka-yan, a private obstetric specialist in Hong Kong, said the service life for some IUDs was between three and 10 years, but the kind of stainless steel IUD commonly used on the mainland in the 1980s was supposedly able to be used for a long time.

"It's understandable that the mainland government massively adopted the long-term IUD, the most cost-effective tool, to reduce the huge population pressure in the 1980s," he said. "But it's a must to provide follow-up checks to monitor the changes and development of the body while the appliance is inside … - it is still a foreign object that a human body would reject."

Kun said that in Hong Kong, when doctors fitted a similar device, a string connected to it would be left outside the patient's vagina.

"If a patient felt discomfort, she could remove the IUD from her body by herself, using the string," he said.

Ai said it was impossible for mainland women to remove the IUDs themselves because strings were not attached. And no government hospitals were allowed to remove them, even if women complained of discomfort or other symptoms.

"The IUD was sleeping in my body for 20 years without any check-ups, even though some uncomfortable symptoms had occurred," she said. "They were all ignored due to a lack of common sense.

"When I found out it might cause a critical problem, it was too late. My inner uterus was severely infected because the device was deeply rooted."

In order to save her life, Ai's doctor suggested the removal of her entire womb, and she agreed.

She said many of her female relatives who underwent IUD operations discovered cervical erosion and other symptoms when they reached 40. All of them needed hysterectomies.

"My domestic helper, a migrant worker who is just in her 30s, was even forced to fit a second IUD after she got pregnant for the second time," Ai said. "She was taken away to hospital by officials for the operation after she was forced to terminate her second pregnancy."

Beijing has long defended the one-child policy as being a vital step in preventing a rapid expansion of population that could lead to food and resource shortages.

Coercion still takes place and those who advocate its abolition and expose abuses of power by local officials, such as blind activist Chen Guangcheng , face persecution. Chen went into exile in the United States after fleeing extralegal house arrest in his hometown in Shandong .

As public pressure mounts over the widespread medical malpractice, some local officials have resorted to paying victims hush money.

Last month, the husband of Sheng Hongxia, a 42-year-old Hubei woman who died after a tubal ligation operation on March 19, received 1 million yuan (HK$1.26 million) in compensation from the local birth control office, reported.

"I promised not to seek any judicial action or further compensation after receiving the 1 million, while local officials said they would allow my second boy to get a residency registration permit," he said.

The policy has also been criticised for favouring the rich over the poor. Critics point out that the penalty for having more than one child is a fine (decided by the birth control departments within local governments), which they say may be affordable for affluent people but out of reach for those of limited means. They also claim many rich people have flouted the law, with scant consequence.

Earlier this month, authorities began investigating reports that Zhang Yimou, one of China's best-known film directors, had had seven children in violation of the one-child policy.

And in February this year, Li Qingshan , a member of the Liaoning committee of the Chinese People's Political Consultative Conference, admitted that, of the three sons and one daughter that he had had by his three former wives, one son and the daughter contravened the policy.

Xinhua reported that Li denied claims, made in a letter on an internet forum, that his families were all living together in a luxury group of villas spanning several hectares behind a People's Liberation Army garrison in Taihe district, Jinzhou .

The one-child policy may have helped avoid more than 300 million births since the early 1980s, but for many, it has been a living nightmare.