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A recent study looks at the impacts of sex-selective abortions on global demographics. Ted Horowitz/Getty Images
  • Some societies have a preference for male children over female or intersex children.
  • Since the 1970s, sex-selective abortions have resulted in skewed sex ratios at birth in favor of males, in a number of countries.
  • A new study predicts that there could be at least 4.7 million fewer females born globally by 2030, and possibly as many as 22 million by 2100, as a result of this trend.
  • The researchers warn that the resulting surplus of men in these countries will cause a “marriage squeeze,” and may also increase antisocial behavior and violence.

The United Nations identifies the sex selection of babies before birth as a harmful practice on a par with child marriage and female genital mutilation.

Prenatal sex selection is usually performed through abortion after a scan has revealed the sex of the fetus.

A report published in 2020 by the United Nations Population Fund states:

“The preference for sons over daughters may be so pronounced in some societies that couples will go to great lengths to avoid giving birth to a girl or will fail to care for the health and well-being of a daughter they already have in favour of their son.”

The bias in favor of male children is “a symptom of entrenched gender inequality, which harms whole societies,” the authors observe.

Previous research estimated that there were 45 million “missing” female births between 1970 and 2017 as a consequence of prenatal sex selection.

More than 95% of these missing births were in China or India.

A new modeling study by the same group of scientists now predicts that in 12 countries known to have skewed sex ratios at birth, there will be an additional 4.7 million missing female births by 2030.

Past trends suggested that the uneven sex ratio at birth, the higher ratio of males to females, will decline in populous countries, such as China and India, in the coming years.

However, the authors report that by 2100, even if there is a projected fall in excess male births over the next 20 years, the total shortfall in female births could be 5.7 million.

In a worst-case scenario, the shortage in female births could be as high as 22 million by the end of the century, an estimate that includes 17 other countries at risk of developing a bias in the sex ratio at birth.

“While the [sex ratio at birth] is projected to decline in some countries, we also provide a more extreme scenario — that [sex ratios] inflate in other countries, such as Pakistan and Nigeria,” said Dr. Fengqing Chao, a statistician at King Abdullah University of Science and Technology, in Makkah, Saudi Arabia, who co-authored the new study.

“Hence, we still need to monitor the possible emergence of imbalanced sex ratio at birth after 2020,” she told Medical News Today.

Dr. Chao developed the predictive models with scientists at the United Nations Population Division, in New York, the National University of Singapore, Centre de Sciences Humaines, in New Delhi, and the University of Massachusetts Amherst.

They based their projections on a database that incorporates 3.26 billion birth records from 204 countries.

The researchers warn that the trends they have identified will lead to a preponderance of men in more than a third of the world’s population — with unknown social and economic consequences.

Their study appears in BMJ Global Health.

The authors note that increased sex ratios at birth, along with excess mortality among girls, have given rise to the concept of “missing women” — when a population has a preponderance of males.

They write that this will lead to demographic problems, such as large numbers of young men being unable to find wives.

In addition, they continue:

“Fewer-than-expected females in a population could result in elevated levels of antisocial behavior and violence, and may ultimately affect long-term stability and social sustainable development.”

The authors conclude that their findings highlight the need to monitor sex ratios at birth in societies that favor sons over daughters.

“A broader objective relates to the need to influence gender norms, which lie at the core of harmful practices such as prenatal sex selection. This calls for broader legal frameworks to ensure gender equality,” they write.

The researchers note that their predictions are based on several assumptions, including estimates of baseline sex ratios at birth and the number of sex-selective abortions.

There is evidence that some societies neglect female offspring in ways that result in excess mortality among girls, compared with boys.

In 2015, for example, a study found that the total number of missing females — a figure that incorporates excess mortality — has risen steadily in recent decades, reaching 126 million in 2010. The figure is expected to hit 150 million in 2035.

Dr. John Bongaarts, vice president and distinguished scholar at the Population Council, in New York, who co-authored this study, said that the future number of missing females due to excess mortality is likely to be much higher than the number of missing female births.

Even so, he added, the new analysis in BMJ Global Health predicts a higher number of missing births than his own study had. “This is largely due to different assumptions about how rapidly sex ratios at births decline to normal in the future,” Dr. Bongaarts told MNT.

The new study is more pessimistic about how quickly sex ratios will decline in countries where they are currently elevated.

However, both studies emphasize the need for gender equality, policies based on monitoring, and advocacy campaigns to combat gender bias.