The desire among parents in India to have sons instead of daughters has created 21 million "unwanted" girls, a government report estimates.
The finance ministry report, published on Monday, found many couples kept on having children until they had a boy.
Authors called this a "subtler form" of son preference than sex-selective abortions but warned it might lead to fewer resources for girls, according to a BBC report.
Son preference was "a matter for Indian society to reflect upon", they said.
The authors also found that 63 million women were "missing" from India's population because the preference for sons led to sex-selective abortions and more care was given to boys.
Tests to determine a foetus's sex are illegal in India, but they still take place and can lead to sex-selective abortions.
Some cultural reasons for son preference were listed, including:
- Property passing on to sons, not daughters
- Families of girls having to pay dowries to see their daughters married
- Women moving to their husband's house after getting married
The states most affected by son preference were Punjab and Haryana, while the least-affected was Meghalaya.
In Punjab and Haryana states there were 1,200 boys under the age of seven for every 1,000 girls of the same age, the authors of the Economic Survey found.