Technology can cause shifts in sex ratios
How ultrasound technology changed baby selection practices in Asia to become more male and also diminished overall health for mothers. Another unanticipated consequence.
The young parents in a remote, dusty, countryside clinic were overjoyed. After gliding an ultrasound wand over the young mother’s belly, the image clearly showed that the soon-to-be-born child was male. They’d wanted a boy, and now their happiness was complete with a son on the way. This scene was repeated often across the land, with unexpected outcomes due to the unanticipated effects of using ultrasound. There’s no question that ultrasound has made pregnancy much safer and healthier all around, but there’s a tradeoff.
Even though it’s an uncomfortable truth, we know that parents prefer boys--this much really isn’t really up for debate, the stats in sex birth ratios show this fairly clearly. It’s well-known that parents tend to prefer having sons (especially as their first born), but nowhere is the preference for sons as obvious as it is throughout Asia, India, the Middle East, and North Africa. Sons are usually preferred because they have a higher wage-earning capacity, they keep the family name alive, and they usually take responsibility for their parents in illness and old age. In India, daughters bring the additional expense of a dowry to be paid out at marriage, and in South Korea and China, deep-rooted cultural values tend to run towards son-preference.
Throughout much of the world there is this bias in child gender preference. Parents much prefer having sons (especially as their firstborn child, and especially if they know they can only have one child).
This preference for boys has led historically to harsh discrimination against girls across the span of their lives—leading to everything from female infanticide, to neglect of girls’ health care and to decreased nutrition for girls overall, which often leads to an early death. Females tend to get the family’s quality food last, with girls being particularly the lowest priority in food distribution within a family.1 [Shafiq]
Like many technologies, the development of ultrasound imaging technology was driven by the desire to have real-time, inexpensive, non-invasive images of the body’s interior. It was recognized as early as 1958 that images could be made with very high-frequency soundwaves—ultrasound—that could give an almost magical ability to peer beneath the skin to see what was going on. After WW2, rapid advances in electronics and piezoelectric materials led to further improvements, improving the ultrasound bodies image from fuzzy gray scans to real-time moving images with amazingly accurate pictures of the body’s interior.
In the 1980s, ultrasound imaging came to many Asian countries becoming the preferred tool for gender identification before birth. Being able to determine if your fetus was likely to be male or female led to a rise in selective abortions to increase the number of sons born into a family. The obvious effect was to almost immediately cause an unprecedented sex-ratio shift.
The sex ratio at birth (SRB) is the number of boys born for every 100 girls. As a metric, it’s universally true there are 105 male births to every 100 female births. But when selective abortions became easily available in 1980, the SRB in South Korea quickly rose to 119 in ten years over the entire country, getting up to 125 in some cities. [Park, 1995] That means that in some places, there are 15-20% more boys than girls. China soon followed, with their country-wide SRB rising to 121 by 2005. [Jiang, et al.] To this day, there is a bulge in the Chinese, South Korean, and Indian populations that’s now a permanent demographic feature of gender selection.
Likewise, India had SRB rates varying by state, up to 125 in Punjab, Delhi, and Gujarat. [Heketh] However, once they recognized the problem, India passed laws to outlaw selective sex abortion. In 1994 India passed the Prenatal Diagnostic Techniques Act, making it unlawful for medical providers to reveal the sex of the fetus to parents. The Act imposes fines and prison time for those caught doing a gender reveal. And slowly, over time, the SRB began to decline. [Bakhtawani]
But a second unanticipated consequence started to show. Even after sex selection abortions were outlawed, mortality grew among women with a first-born daughter. Why? Because “As a result of strong son preference, such women are more likely to engage in fertility behavior that adversely affects their health.” [Milazzo] Mostly, the increase in mortality and poor health among women after the birth of a first-born daughter stems from the pressure to have another baby as quickly as possible, driven largely by the desire to have a son. When looking at women who have had a first-born daughter, compared to women have had first-born sons, such women are 5.1% more likely to want more children and 6.8% less likely to be sterilized after their daughter’s birth. They also develop anemia at much higher rates than their son-bearing peers. Among women who have had a first-born daughter followed by a second-born daughter, the pressure to have yet another child is immense.
But then in 2018, NIPT (non-invasive prenatal testing, which uses only a blood sample taken from the mother to identify fetal DNA) became much lower in cost, and is more accurate than ultrasound. [Bowman-Smart] It was initially developed to detect birth defects (primarily genetic issues such as Down Syndrome or other genetic disorders).
Such a test is easy and fast. And so far, this technology is NOT banned under any legal sex-selective abortion. A woman could discover her baby’s gender in private, and then request an abortion for economic reasons, hiding the sex-selection reason behind a plausible--and legal--story.
Does it matter that sex-ratios are so far from the historic norm? There are a number of consequences which could result from highly imbalanced ratios of men and women. These present a risk to men, a risk to women, risks to family structures and risks to society as a whole.
The obvious consequence of gender imbalance is a large number of men without partners.
Effects on men: Many men will have to delay marriage or find it impossible to find a suitable partner. This will have a long-lasting impact on younger men. Not only will they be affected by a skewed sex ratio for their generation, but this discrepancy will create a backlog of men from the previous generations searching for marriage partners. As a consequence, a significant number of men will have to forego marriage altogether. There is also a deep concern than not only will there be an excess of men who do not marry and have their own family, but that the most affected mean will be those of lowest socioeconomic status, the most uneducated and those with fewer opportunities. This might well lead to significant social stability and security concerns. (And it’s very possible that women will “marry up” in society, leaving the men with least resources disproportionately affected.)
One of the most common reasons for son preference is to preserve the family name over generations. This will likely not happen in families where sons do not marry.
Effects on women: Women could also suffer serious effects as well. It’s possible that a women’s value as a wife or mother might become increasingly important. This may deny her alternative life pathways, such as remaining single or becoming more career-focused.
Women will feel increased pressure to marry or have children earlier in life (possibly closing off different economic or work opportunities).
More worrying—women may be at increased risk of violence (emotional, sexual or physical) or trafficking as the result of being less a part of the population. [Hudson and De Boer]
Effects on society: Social structures might have profound changes as well. These kinds of imbalances have created markets for trafficking women from other countries, leading to increased violence and exploitation of women. While the analysis of the data about unbalanced SRBs is complex, some scholars believe that gender imbalances have led to increased violence and crime against women, including sexual assault and rape. As an example, in China, the bride shortage SRB mismatch was reported to have led to cross-border marriages, multiple cases of female abduction to get brides, and even a return to an older, traditional system in which families would adopt infant girls to raise them as future brides for their sons. [DasGupta and Shuzhuo]
It's clear that the ability to introduce a useful technology (such as ultrasound for pregnancies) can have huge beneficial effects. But with every technology comes another potential use—in this case, sex determination and selecting for male babies.
And in this case, the consequence (a huge number of ‘excess men’ in a population) wasn’t obvious for several years. Look the above chart for details.
Technology isn’t introduced into a country instantly, but takes some time to deploy. Likewise, even after widespread adoption, finding the gender selection use takes time to happen. But once it does take place, the pace is rapid. (See the above chart between the years 1985 and 1990.)
To make things worse, once a problem is noticed, it takes a significant amount of time for laws and regulation to take effect. And it leads to a deep issue in unanticipated consequences: Technology moves much faster than regulation. Even if a decision has a negative consequence, correcting the issues can take a long, long time. In India, after the 1994 regulation of ultrasound for gender determination is still took 20 more years for the effect to change the SRB. [Bhaktwani]
And, of course, even if ultrasound becomes unavailable, technology can still advance. The blood sample technology introduced in 2018 doesn’t need ultrasound. It remains to be seen if this will lead to a new shift in nationwide SRBs, and a new generation of excess men and fewer women.
---- References ----
Bhaktwani, A. (2012). The PC-PNDT act in a nutshell. Indian Journal of Radiology and Imaging, 22(02), 133-134.
Bowman‐Smart, Hilary, et al. "Sex selection and non‐invasive prenatal testing: A review of current practices, evidence, and ethical issues." Prenatal Diagnosis 40.4 (2020): 398-407.
Chandrasekarayya, T., Sujatha, D. S. Declining sex ratio in India: Causes and consequences. AJSS v 8, n 1, Jan-Jun 2009, pp. 75-82
Chun, Heeran et al. “Understanding Women, Health, and Social Change: The Case of South Korea.” International Journal of Health Services 36 (2006): 575 - 592.
Das Gupta, Monica, and Li Shuzhuo. "Gender bias in China, South Korea and India 1920–1990: Effects of war, famine and fertility decline." Development and Change 30.3 (1999): 619-652.
Espíndola-Hernández, P., Castaño-Villa, G. J., Vásquez, R. A., & Quirici, V. (2017). Sex-specific provisioning of nutritious food items in relation to brood sex ratios in a non-dimorphic bird. Behavioral Ecology and Sociobiology, 71(4), 65.
Jiang, Q., Yu, Q., Yang, S., & Sánchez-Barricarte, J. J. (2017). Changes in sex ratio at birth in China: a decomposition by birth order. Journal of biosocial science, 49(6), 826-841.
Hesketh The consequences of son preference and sex-selective abortion in China and other Asian countries.
Hudson, Valerie M and den Boer, Andrea (2005) Missing Women and Bare Branches: Gender Balance and Conflict. Environmental Change and Security Program Report (11). pp. 20-24.
Milazzo, Annamaria. "Why are adult women missing? Son preference and maternal survival in India." Journal of Development Economics 134 (2018): 467-484.
Park CB, Cho NH. Consequences of son preference in a low fertility society: imbalance of the sex ratio at birth in Korea. Popul Dev Rev 1995;21:59–84
Sen A. Missing women revisited. BMJ 2003;327:1297–8.
Shafiq, A., Hussain, A., Asif, M., Jameel, A., Sadiq, S., & Kanwel, S. (2021). Determinants of Gender Disparity in Nutritional Intake among Children in Pakistan: Evidence from PDHS. Children, 9(1), 7.
You can find other examples of this kind of gender bias –search on Google for “nutritional discrimination” or “nutritional bias.” You can find astounding differences in feeding preference patterns not just in humans, but notably in many bird species. For instance, the Thorn-tailed Rayaditos bring more high-quality food to the nest when there are more males in the brood than females, and even Zebra finches and albatrosses preferentially feed males over females in the same nest. [Espindola-Hernández, et al]