One of the world's least controlled abortion regimes will be tightened next month when the Guiyang introduces a pilot program aimed at halting the widespread termination of female fetuses.
The new policy bans doctors from carrying out abortions on most women who are more than 14 weeks into pregnancy.
In many cases, the parents delay making a decision until ultrasound checks can determine the sex of their child. If it is a boy -- who can carry on the family name -- there is more likelihood that the pregnancy will be completed.
If it is a girl -- considered less valuable by many families -- there is a greater chance of abortion.
The demographic distortions of gender bias are thought to have been greater in China because of the country's one-child policy.
The policy has led to fears of social instability as future generations of men are unable to find wives, and the sex trade and trafficking of women becomes more lucrative.
China's laws do not set time limits for abortions, reflecting the government's long-running campaign to curb the growth of the world's largest population.
Ministry of Health protocols for gynecology clinics say pregnancies can be terminated until 24 weeks.
There are reports of doctors carrying out abortions at even later stages.
Last year, 117 boys were born for every 100 girls in China.
In 1982, shortly after Beijing's introduction of the one-child policy, the ratio was similar to the global average of 105 boys for every 100 girls.
Worried by the long-term impact of this trend, President Hu Jintao (
Three months ago, government officials began gathering information about abortion laws in other countries and canvassing international organizations for their views on the issue.
The main recommendation to emerge was for a time limit.
Guiyang is the first to put the new thinking into practice.
Under new regulations which come into force on Jan. 1, the only abortions that will be permitted after 14 weeks are those in cases where the spouse has died, the couple have divorced or the fetus is proven to have a genetic disfigurement or disease.
Any doctor or hospital administrator found to have violated this rule faces a penalty of up to six times their earnings.
Guiyang's officials said the new regulations were necessary because the boy-girl ratio on the city was between 129:100 and 147:100 for couples seeking to have a second or third child.
This is permissible in some provinces, despite the one-child policy being rigorously enforced in big cities.
International development officials have given a cautious welcome to Guiyang's announcement, noting that the health risk to mothers is 10 to 20 times lower if abortions are carried out in the first trimerster rather than the third trimester.
Critics, however, point to uncertainties about implementation and continued concerns about what one-child policy.
Because of the stiff penalties for second children, many couples have unregistered babies. There may be as many as a 100 million of these "illegal children."