A report by a British charity says there has been a sharp decline in the number of young girls to boys in some parts of India in the last five years. Anjana Pasricha reports from New Delhi, the cultural preference for sons has led to a skewed ratio of girls to boys in India as many families abort female fetuses.    

The study in north and northwest India found that the ratio of girls under six years of age has plunged since 2001 when the last nationwide census was conducted.

The report "Disappearing Daughters" has been conducted by ActionAid and Canada's International Development Research Center.

It says in three of five states surveyed, the number of girls had declined to less than 800 for every 1000 boys compared to the nationwide average of 950 girls.

The report says the decline is happening in both rural and prosperous urban areas, showing that the preference for sons cut across economic and social classes.

The report's main researcher, Jyoti Sapru, says urban families (in some areas like the northern Punjab state) are increasingly opting for small families, squeezing the space for girls.

"For example in urban Punjab one finds that families articulate the size that they ideally would like as one child, and that one child really is becoming a one-son family - it is no more space given for one girl, one boy,"  Sapru said.

The report says many parents do whatever they can to avoid having daughters. 

Some abort female fetuses after using ultrasound technology to determine the sex of the child despite a 1994 law that bans such tests.

It says survival rates for of girl babies are also hitting an all-time low due to neglect of their health. 

The preference for boys over girls is rooted in a culture that looks upon girls as financial burdens because parents give a dowry when they marry.

Sapru says that preference is becoming accentuated as people begin to spend larger amounts on the education and health of their children.

"Somewhere the investment in a daughter from the point of view of health and education seems to be becoming more of a liability for families, coupled with dowry for a girl," Sapru said. "They would rather put money in their son's education and health, and his marriage and his job."

Over the past decade, India has launched several public campaigns to educate people about the rights of girls - but progress has been slow, especially in the north of the country. 

The "Disappearing Daughters" report has called on the government to ensure tougher enforcement of laws to check the practice of aborting female fetuses. But it says that in the long term, cultural attitudes need to change. 

The British medical journal, Lancet, has estimated that half a million female fetuses are aborted every year in India.