The UN estimated on Monday, that Asia is "missing" about 96 million women -- the vast majority in China and India -- who died from discriminatory health care and neglect or who were never born at all.
Female infanticide and sex-selective abortion have caused a severe gender imbalance in Asia, and the problem is worsening despite rapid economic growth in the region, the United Nations Development Programme (UNDP) report said.
"The old mindset with its preference for male children has now combined with modern medical technology" that makes it easier to predict and abort unborn girls, said Anuradha Rajivan, the report's lead author.
"It is not just female infanticide but sex-selective abortion of unborn girls that cause so-called 'missing' females," she said, contrasting the issue with recent improvements in female life expectancy and education.
The UNDP report found that East Asia had the world's highest male-female sex ratio at birth, with 119 boys born for every 100 girls.
This far exceeded the global world average of 107 boys for every 100 girls.
"Females cannot take survival for granted," it said.
"Sex-selective abortion, infanticide, and death from health and nutritional neglect in Asia have left 96 million missing women... and the numbers seem to be increasing in absolute terms."
The regional figure was skewed by enormous birth gender disparities in China and India, which between them accounted for about 85 million of the report's "missing" figure.
The number was calculated from the actual sex ratio in the population compared to what it would theoretically be, if equal treatment were given to the sexes during pregnancy, birth and afterwards.
Despite Asia's robust economic growth, the report found that millions of women remained shut out of the benefits of greater prosperity.
The region, and especially south Asia, ranks near the worst in the world -- often lower than sub-Saharan Africa -- on issues such as protecting women from violence, as well as access to health, education, employment and political participation.
"Today, the Asia-Pacific region is at a crossroads," the report said. "Whether gender equality is pushed aside or pursued with greater energy amid the economic downturn depends on actions taken or not taken now by governments."
The report, launched on International Women's Day, focused on the need to improve women's rights in three key areas: economic power, political participation, and legal protection.
Helen Clark, the former prime minister of New Zealand who now heads the UNDP, said both genders would benefit if progress were made in all three sectors.
"Female participation in society can improve a country's economic position, and you can't achieve your development goals unless you have females as part of the equation," she said.
"Countries who don't do that will always fail to fulfill their potential."