The suspended death sentence handed down to Zhang Shuxia, former deputy director of obstetrics at Fuping County Maternal and Child Healthcare Hospital in Shaanxi province, for selling seven babies once again highlights the problem of child trafficking.

Child trafficking is a global problem. Up to 4 million women and girls are bought and sold into marriage, prostitution and slavery every year. According to UNICEF, more than 1 million children, most of them girls, are forced into the sex trade every year.

Commercial sexual exploitation of children is increasing across the world. Instead of showing signs of abating, as we hope, child prostitution is growing. There are many reasons for this, including increasing trade across borders, rising poverty and unemployment, low social status of girls, lack of education (including sex education) of children and their parents, inadequate legislation, lack of or poor law enforcement, and the eroticization of children by the media, a phenomenon increasingly seen in industrialized countries.

The UN Special Rapporteur on Violence Against Women has called attention to the levels of state participation and complicity in the trafficking of women and children across borders. Because of their often undocumented status, language deficiencies and lack of legal protection, kidnapped children are particularly vulnerable in the hands of smugglers and corrupt and heartless government officials.

Special social and cultural reasons also play a role in forcing children into the sex trade in different regions. In many cases, children fleeing abusive homes in industrialized countries are forced to enter the sex trade. In Eastern and Southern African countries, many children who lose their parents to AIDS lack the protection of caregivers and are, therefore, more vulnerable to sexual abuse and exploitation.

Although children from Eastern European countries, such as Russia, Poland, Romania, Hungary and the Czech Republic, are increasingly vulnerable to exploitaion, the highest number of children forced to work as prostitutes is in Asia. Traditional practices that perpetuate the low status of women and girls in society are at the root of this problem.

Child sex tourism has become a worldwide phenomenon, but it is concentrated in Central and South America and Asia. Thailand's Health System Research Institute reports that children comprise 40 percent of the prostitutes in the country. Apart from the moral and ethical implications, the impact that sexual exploitation has on children's health and development demands urgent attention.

Sexually exploited children are vulnerable to sexually transmitted diseases and HIV/AIDS. In addition, because of the conditions in which they live, sexually exploited children can easily become victims of malnourishment, develop feelings of guilt and inadequacy, and suffer from depression.

Throughout the world, many individuals and NGOs are working intensely to protect children's rights, and many times, their work brings them into conflict with governments and powerful interest groups.

Among the United Nations agencies, UNICEF has been particularly active in highlighting this phenomenon and in addressing the root causes of sexual exploitation, by providing economic support to families to free their children of the risk of sexual exploitation, by improving access to education - particularly for girls - and by becoming a strong advocate of the rights of the child.

The work of UN agencies and NGOs should complement the efforts of governments to stop child trafficking and sexual exploitation of children. Such actions should include preventing children's sexual exploitation through social mobilization and awareness building, providing social services to sexually exploited children and their families, and creating the legal framework and resources for psychosocial counseling and for the appropriate prosecution of perpetrators.

The elimination of sexual exploitation of children is a daunting task, but one that is achievable if effective programs are put in place. Only when sexual exploitation of children is eliminated can we be able to say that the world's children are exercising their right to a healthy and peaceful life.

The author is an international medical consultant and co-winner of an Overseas Press Club of America award.