Today, around 140 million women are believed to be "missing" around the world – the result of son preference, including gender-biased sex selection, a form of discrimination. Since the 1990s, some areas have seen up to 25 per cent more male births than female births. The rise in sex selection is alarming as it reflects the persistent low status of women and girls. The resulting gender imbalance also has a damaging effect on societies. Instances of increased sexual violence and trafficking have already been linked to the phenomenon. UNFPA is calling for renewed attention to the issue at a global level, and is accelerating efforts to develop programmes and policies that end all forms of discrimination, including son preference and gender-biased sex selection.

Topic summary

How do we know sex selection is taking place?

Gender-biased sex selection can be measured using sex ratio at birth, a comparison of the number of boys born versus the number of girls born in a given period. The biologically normal sex ratio at birth can range  from 102 to 106 males per 100 females. When many more boys are born than girls, it is a sign that sex selection is taking place. Ratios as high as 130 boys per 100 girls have been observed.

The 2020 State of World Population Report indicates that more than 140 million females are considered missing today as a consequence not only of gender-biased sex selection but also of postnatal sex selection.

History of sex selection

Sex selection is not new. Census data from India, for example, show an imbalance in sex ratios among children in the early 20th century. Such disparities almost always reflect a preference for sons.

In the past, son preference may have resulted in the neglect or killing of female infants. However, since the early 1980s, ultrasounds and other technologies have enabled parents to detect the sex of a foetus during prenatal screenings; those who prefer sons may arrange to abort female foetuses. This has accelerated sex-ratio imbalances at birth in parts of the world.

Today, gender-biased sex selection can take place before a pregnancy is established (for example, preimplantation sex determination and selection, or “sperm sorting” for in-vitro fertilization) or during pregnancy (sex-selective abortion).

It is important to note that while technology has enabled an additional method for sex selection, it is not the root cause of the problem. In places where son preference is not observed, the availability of these technologies does not lead to trends in gender-biased sex selection.

Postnatal sex selection also continues to occur; this is measured by excess deaths among female infants and young girls, reflecting the continued discrimination against and neglect of female children.


Causes and consequences

Son preference is an expression of the low value that girls are afforded in some communities. It often reflects discriminatory socio-economic practices and traditions. For example, in some places, sons alone inherit property, and they alone are expected to care for ageing parents, conduct funeral rites and carry on the family name. Meanwhile, daughters may be considered a burden, particularly if an expensive dowry is required for them to get married.

Such traditions place huge pressure on women to produce sons. Some women may even face abandonment or violence if they have daughters instead of sons. Studies have shown that unwanted girls may endure neglect or be deprived of opportunities – creating a further disincentive for mothers to have daughters, since they do not want to see their children suffer. Son preference ultimately affects women’s sexual and reproductive lives, with implications for their health and survival.

The consequences of son preference, the low value of girls and gender-biased sex selection are far-reaching.

In China and India, men who would like to get married may not be able to, and there are signs that the upcoming “marriage squeeze” could have serious social consequences. Instances of increased sexual violence and human trafficking have been linked to this situation. And there has already been an increase in “cross-border brides” – women and girls migrating, or being trafficked, into areas where there are fewer women than men. These women may be unable to speak the local language, and may fall under intense pressure to produce male children.

Solution: Gender equality and the empowerment of women and girls

Some countries have outlawed or restricted the use of modern technologies for sex-selection purposes. However, such prohibitions are often difficult to enforce, and they could drive demand for these technologies underground.

Tackling the root cause of son preference and gender-biased sex selection – gender inequality – may be more effective, and it yields benefits for all of society. Empowered women and girls contribute to the health and productivity of families and communities and improve prospects for future generations. Awareness of their value and contributions is essential to changing behaviours.

Strong political commitment and community-level action are also needed. Access to education and reproductive health services helps to empower women and improves their health, productivity and status. Other policies can also play a key role. Laws permitting daughters to inherit property, for example, can signal that men and women have equal rights.

Such efforts have been effective in several countries and communities. In the Republic of Korea, for example, a strong women’s movement, coupled with economic development and legal reforms to gender-unequal laws, helped return imbalanced sex ratios to a natural level.

UNFPA’s response

For more than 20 years, UNFPA has campaigned against the phenomenon, sounding the alarm over son preference and helping communities advocate against gender-biased sex selection. UNFPA co-led efforts with the World Health Organization to develop and release the first-ever UN-wide policy statement on the issue in 2011.

And in March 2017, UNFPA, with funding from the European Union, launched the Global Programme to Prevent Son Preference and Gender-Biased Sex Selection, the first global effort of its kind. The programme will work with governments and local partners to gather data about unequal sex ratios at birth in Asia and the Caucasus, and will design human rights-based and gender-equality focused interventions. 

Many governments are already working closely with UNFPA to address son preference. In India, for example, collaborations with the judiciary, health sector, law enforcement, media, researchers and community members – including religious organizations – have resulted in many good practices  worthy of sharing.

And in Viet Nam, UNFPA supported the collection and analysis of data on sex ratio at birth, revealing skewed sex ratios, and then helped ensure the issue was put on the policy agenda. In Armenia, Albania and Azerbaijan, UNFPA is working with governments to support country-wide research on the issue. Public advocacy campaigns are also being rolled out to combat traditional attitudes towards girls.

Updated 27 July 2020.