For all the social campaigns and awareness drives to end sex selection in India, the preference for sons is still going strong. In recent years, though, it has taken a more subtle form.

Many Indian parents are opting to continue having children till they have the desired number of sons, shows the economic survey 2017-18 (pdf), released on Jan. 29. The survey calls this the son “meta” preference, and suggests that while it avoids sex-selective abortion, it can still hurt female children by reducing the resources available to them.

“Families where a son is born are more likely to stop having children than families where a girl is born. This is suggestive of parents employing ‘stopping rules’,” says the survey, which was led by chief economic advisor Arvind Subramanian.

As a result of this son meta preference, the economic survey estimates that India could have as many as 21 million “unwanted girls,” i.e., girls whose parents wanted to have sons instead.

To come to this conclusion, the survey looked at an indicator called the sex ratio of the last child (SRLC), using decades of data from the demographic and health survey. This indicator is likely to be heavily skewed in favour of boys if the society has a preference for sons—unfortunately, exactly what is seen in India.

According to the World Health Organisation, the natural “sex ratio at birth” is considered to be 1.05. This means that at birth, on average, there are 105 males for every 100 females.

The following chart shows how, in India, the sex ratio changes with each child that is born. The panel on the left shows that the sex ratio of the first child in Indian households with more than one child is 1.07, fairly close to the biologically determined natural sex ratio.

But the sex ratio of the last child for first-borns is 1.82—heavily skewed towards boys, according to the authors of the survey. The contrast becomes clearer when India is compared to a country like Indonesia, where the SRLC is close to the ideal sex ratio, regardless of birth order and whether or not the child is the last to be born.

Economic Survey 2017-18

When the survey analysed this indicator by state, Meghalaya stood out because the sex ratio at birth and the SRLC were both close to the benchmark. But the authors also found that states that don’t practice sex-selective abortions, such as Kerala, did demonstrate a son meta preference, recording a skewed SRLC. And the northern states of Punjab and Haryana showed both extremely high son preferences and son meta preferences.

Economic Survey 2017-18

“In some sense, once born, the lives of women are improving,” the survey says, “but society still appears to want fewer of them to be born.”