The United Nations is calling on governments to address sex selection favoring boys, saying it fuels a culture of discrimination and violence.

Five U.N. agencies, including the World Health Organization and the U.N. Children's Fund, said Tuesday there is huge pressure on women to produce sons. This pressure not only directly affects women's reproductive decisions, but also puts them in a position where they must perpetuate the lower status of girls through son preference.

The agencies say the preference for boys in many parts of South, East and Central Asia has led to ratios as high as 130 boys for every 100 girls born. They say this imbalance leads to an increase in violence against women. For instance, the lack of women available for marriage in some areas may lead to the trafficking of women.

The U.N. says women are left to bear the consequences of giving birth to an unwanted baby girl, including violence, abandonment, divorce or even death.

In some countries, pre-natal sex determination through the use of ultrasound is banned. But the U.N. says such restrictions are often bypassed by the use of “clandestine procedures that put women's health in jeopardy.”

The U.N. agencies are calling on governments to set guidelines on the use of technology for health professionals, enact support measures for women and girls, and undertake other legal and awareness-raising actions.