Vietnam and Nepal are the latest Asian countries to show a trend toward fewer newborn girls than boys because deeply rooted cultural traditions lead to a misuse of medical technology, a UN agency study found.

Asians, particularly in India and China, have long been known to practice pre-natal son selection by using ultrasound and amniocentesis and then aborting unwanted female foetuses, the United Nations Population Fund said. ?I don?t think we are damning the technology and one shouldn?t. But unfortunately the technology is being abused,? UNFPA deputy executive director Purnima Mane said in an interview on a weekend visit to Vietnam. Ultrasounds and amniocentesis help doctors detect birth defects and the health and development of a foetus.

Many Vietnamese want to have a son as their first child, part of a tradition to continue family lineage, for ancestor worship and security in old age for parents.

For Vietnam, which has a population of 85 million, ?sex ratio at birth is not a significant problem now but could be within a decade?, the researchers said. In Nepal, which has a population of about 30 million, researchers said women living near the border with India could go to clinics in India that flout prohibition on sex selection.

In these predominantly rural societies, an increase in trafficking of women and domestic violence were possible consequences of gender imbalance.