Experts have suggested more effective action against illegal pregnancy gender scans and discrimination of women so as to curb the sex ratio imbalance in China.

The country's sex ratio of newborns stood at 119.45 boys to 100 girls in 2009, according to the latest figure announced by the National Bureau of Statistics (NBS) in February.

Prof. Zhai Zhenwu, dean of the School of Sociology and Population, Renmin University of China in Beijing, said gender discrimination was the major cause of the problem.

"An imbalanced sex ratio is widely found in the countries and cultures that favor boys," Zhai said.

Rural areas have reported the most serious sex ratio imbalance, he said.

Chinese families prefer boys mostly because, traditionally, girls will leave the family after getting married and the parents will have no one to look after them in old age, he said.

"Adequate social security, especially a pension system in rural areas, will ease people's concerns on this issue," he said.

Technically, widespread use of ultrasound scans during pregnancy has made gender scans easier and more accurate.

Although the country bans ultrasound scans to distinguish infants' gender, it still occurs.

"Some private practicing doctors and small hospitals are providing this illegal service. In recent years, the services have become very sophisticated and gender scans can be arranged at the client's home," Zhai said, adding that it was very difficult to catch the offenders.

Prof. Yuan Xin, director of the Population and Development Institute of Nankai University in Tianjin, said stopping discrimination against women will help curb the sex ratio imbalance.

"Chinese women still lag behind men in career development, political life and in family life, except for the education level," he said.

"If women's social status improves, parents will feel better about raising a female child," he said.

A report issued by the Chinese Academy of Social Sciences last December estimated that China's male population at marriageable age will be 24 million more than female counterparts in 2020.