According to the analysis appeared in the Canadian Medical Association Journal (CMAJ), India along with China and South Korea are set to witness a 10 to 20 per cent surge in young male population and this imbalance will have huge societal repercussions.
A preference for sons combined with easy access to sex-selective abortions has led to a significant imbalance between the number of males and females born in these nations.
The sex ratio at birth (SRB) -- the number of boys born to every 100 girls -- is consistent in human populations in which about 105 males are born to every 100 females.
However, with the advent of ultrasounds that enable sex-selection, the SRB in some cities in South Korea climbed to 125 by 1992 and it is over 130 in several Chinese provinces from Henan in the north to Hainan in the south.
In India, similar disparities exist, with sex ratios as high as 125 in Punjab, Delhi and Gujarat in the north but normal sex ratios of 105 in the southern and eastern states of Kerala and Andhra Pradesh.
A recent study in India showed that for second births with one preceding girl the SRB is 132, and for third births with two previous girls it is 139, whereas sex ratios are normal where the previous child was a boy.
In 2005 in China, "it was estimated that 1.1 million excess males were born across the country and that the number of males under the age of 20 years exceeded the number of females by around 32 million," wrote the study authors led by Prof Therese Hesketh of UCL Centre for International Health and Development in London.
"A consistent pattern in all three countries is the marked trend related to birth order and the influence of the sex of the preceding child," they said.
If the first or second born are girls, couples will often sex select to ensure the second or third child is a boy, they noted.
The societal implications mean that a significant percentage of the male population will not be able to marry or have children because of a scarcity of women.
Currently in China, 94 per cent of unmarried people aged 28 to 49 are male, 97 per cent of whom have not completed high school, and there are worries that the inability to marry will result in psychological issues and possibly increased violence and crime.
Policy makers in China, India and South Korea have taken some steps to address the issue, such as instituting laws forbidding fetal sex determination and selective abortion, but more can be done.
"To successfully address the underlying issue of son preference is hugely challenging and requires a multifaceted approach," wrote the authors.