Peking — Jia Lili is very concious of her appearance. For 40 minutes every day she stands in front of the mirror, making sure she looks her best. Only then will she agree to go to kindergarten.
Like many of her contemporaries, four-year-old Lili is an only child, the center of her family's attentions. She has the potential, say Chinese authorities, of growing up a spoiled brat.
''Single children are the sun in the family, and the parents and grandparents simply the planets orbiting around them,'' one Shanghai educator says.
But the prospect of a nation of overindulged children is only one of the complications that China's policy of one child per family is causing.
With its population already tipping the 1 billion mark, China's modernization program is in danger of coming to a standstill as feeding, clothing, and housing the nation eat up more and more of the country's resources.
If the Chinese government's goal of containing the population within the 1.2 billion mark until the end of the century is to be achieved, China's annual population increase has to be maintained at under 1 percent until the year 2000.
But faced with the prospect of 78 million newlyweds in the next three years, and their potential offspring, the Chinese government has been forced to take increasingly unpopular measures to ensure the widespread practice of its one-child-per-couple policy. (The policy is not expected to become law until the end of this year.)
Family planning has been seriously promoted only since 1971, after the nation's population jumped by 122 million in the early years of the Cultural Revolution. Under the marriage law passed in 1980, all couples are required to practice some form of contraception.
First introduced about three years ago, the national policy called on urban dwellers and government employees to have only one child. This has been enforced with special privileges and bonuses for single-child families and sanctions against those couples who overstep the limit. Rural dwellers have been ''strongly encouraged'' to have one child, but two have been accepted in many areas.
But recent adoption of the ''job responsibility system,'' which raises opportunities for sideline, privately owned industries in rural areas, has meant that a household can increase its income if the family has many children and puts them to work. This new policy thus strengthens the traditional preference both for large families and for sons.
The upsurge in larger families has meant that some provinces are now forcing women who become pregnant for a second time to have an abortion, and are ordering couples that already have more than one child to be sterilized. Two provinces - Guangdong, bordering Hong Kong, and the central province of Shanxi - have already made it illegal to have more than one child.
''The one-child policy is being carried out largely through education and persuasion, but some practical measures are needed,'' a senior Chinese official said recently.
The problem of enforcing the policy, especially in rural areas, is further complicated by a rise in female infanticide that it is believed to have incited.
Always practiced to some extent in rural areas, the killing of female babies has risen in the countryside, where according to one recent survey, the imbalance between the sexes in some districts is as high as five male children to every one female child.
The government has denied that female infanticide is as bad as some reports in the Chinese press suggest. But the problem is considered serious enough by the government for Premier Zhao Ziyang at the party congress last November to say, ''We must protect infant girls and their mothers. The whole society should resolutely condemn the criminal activities of female infanticide and maltreatment of mothers.''
In the cities, where there is less traditional and economic pressure to have a son, the one-child policy has been the most successfully implemented. In Peking there are already 500,000 children under the age of 14 registered as only children. And at a recent competition sponsored by the city's public health bureau and family-planning committee, more than 600 of these were judged to be ''model'' only children.
As part of a drive to encourage family planning and better child-raising, the competition was judged on the basis of good health and an intelligence test taken by the competitors, all under seven years of age.
''We try not to dote on her at home,'' said the mother of one three-year-old prizewinner. ''We feed her regular meals and teach her good manners. She learned to put on clothes herself when she was only two years old.''
There are more than 20 child-care stations in Peking that provide advice and guidance for parents on how to care for their children and avoid the spoiled brat syndrome. In some districts, lectures are given to grandparents who often look after a child as most parents work full time.
''But there are still parents who don't know the proper methods of child-rearing,'' a doctor judging children at the one-child competition said. ''So we are hoping to promote better child-rearing through things like this contest.''