In a society that values the birth of a baby boy over that of a girl it's still an alarming fact that an increasing number of Indian families with one girl are aborting subsequent pregnancies when prenatal tests show the baby is also female.
It may be a surprise to some that the decline in the number of girls is more pronounced in richer and more educated households, according to research published in the medical journal Lancet.
These figures show that a law passed in 1996 banning gender testing on a fetus has been largely ineffective, the study said.
In India, there is a huge cultural preference for boys mainly because of the enormous expense in marrying off girls and paying elaborate dowries.
Officials have acknowledged that current laws have proved inadequate at combating the widening sex ratio gap.
The study found that between four million and 12 million girls are thought have been aborted between 1980 and 2010.
Raw data from India's census released in March showed the country's population comprised of 914 girls under age six for every 1,000 boys.
Only a decade ago, many were horrified when the ratio was 927 to 1,000.
Researchers studied census data and government surveys of more than 250,000 births to conclude that gap is even wider in families that already have a girl.
The ratio was 906 girls under six to every 1,000 boys in 1990 and had declined further by 2005, when it was 836 to every 1,000.