A staggering 21 million “unwanted” girls are the result of Indian parents determined to have a son.

India’s finance ministry has found that many couples are continuing to have children until a son is born, the BBC reported.

The report labelled the trend a “subtler form” of son preference than gender-based abortions.

Testing for a foetus’ sex is illegal in India, but it still happens and can result in sex-selective abortions.

Researchers looked at the sex ration of the last child in compiling the report.

They found it weighted heavily towards males, indicating parents continued having children until they got the desired number of sons.

Historically Indian parents have desired sons – who are regarded as breadwinners and family heirs.

Girls are widely seen as a financial burden in a society where the tradition of offering a dowry at marriage continues.