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A recent study published in the Journal of Public Economics suggests that the ratio of men to women in local dating markets may influence the health of mothers and their newborns. Having a higher proportion of available male partners is associated with more stable romantic relationships and better pregnancy outcomes. These findings provide evidence that social and demographic environments play a role in shaping early life and reproductive health.
The study was conducted by Krzysztof Zaremba, an assistant professor at ITAM Business School in Mexico City. He sought to analyze romantic partnerships through an economic lens to understand how partner availability shapes well-being.
“I’ve always been intrigued by the idea that dating works like a market, subject to the economic principles of supply and demand,” Zaremba told PsyPost. “I wanted to understand how the supply of potential partners shapes what people can achieve in their dating lives.”
Economic theory indicates that when men are relatively scarce, women tend to have less leverage in relationships. This dynamic can affect family formation, the resources available to women, and their ability to plan pregnancies.
In the United States, dating market imbalances are particularly pronounced among Black communities. For every 100 Black women of childbearing age, there are only roughly 89 Black men, compared to a nearly equal ratio among White adults. A large portion of this imbalance stems from high incarceration rates and higher mortality among young Black men.
“At the same time, one population in the United States faces a severe shortage of potential partners: there are considerably fewer young Black men than young Black women, largely due to incarceration,” Zaremba explained. “I wondered what the consequences of this imbalance are for health, and whether it can help explain the large health disparities we observe between Black and White Americans.”
The stark demographic reality surprised the researcher when examining the national data. “First, the sheer scale of the missing men: in the United States, there are only 89 Black men for every 100 Black women of childbearing age, compared with 102 White men per 100 White women,” Zaremba noted. “This is largely due to incarceration, but also to high mortality among young Black men.”
Studying the relationship between dating markets and health presents a major challenge because adult sex ratios are often tied to local economic or social conditions. For instance, areas with high crime rates might have both fewer men due to incarceration and worse health outcomes due to stress. To address this issue, Zaremba looked at the natural randomness of the sex of babies at birth.
“The challenge is that places with more men also differ in many other ways, so it’s hard to know what’s really driving any differences we see,” Zaremba said. “So I came up with a trick: using the sex ratio at birth. Your sex at birth is random, and because Americans move less than people often assume, the sex ratio of babies born in a county largely determines the sex ratio of that county’s adult dating market decades later. That randomness lets me isolate the causal effect of partner availability.”
Because the odds of a baby being born male are roughly 51 percent, small communities experience random fluctuations in how many boys and girls are born in any given year. Zaremba was surprised by how persistent these childhood demographic patterns were over time. “Second, how little people move,” he noted. “The sex ratio at birth remains an important predictor of the sex ratio in the same county up to 35 years later.”
The author used U.S. birth record data from 2011 to 2019 to track these patterns, analyzing roughly 7 million births. He defined a local dating market based on a person’s county, race, and five-year age group. The analysis focused on communities with birth cohorts between 200 and 5,000 people to capture random fluctuations in sex ratios without the numbers balancing out completely, controlling for factors like maternal age and county characteristics.
By linking the historical birth sex ratio of a generation to later health outcomes during pregnancy, the study provides evidence that partner availability shapes reproductive health. An increase in the proportion of men did not alter the overall birth rate, but it shifted the context of those births toward marriage.
“When there are more men around, women hold a stronger position in the dating market,” Zaremba summarized. “They end up in more stable relationships: they’re more likely to be married and less likely to have children outside of marriage. They’re also healthier: they have lower rates of sexually transmitted infections and give birth to healthier babies.”
Specifically, a modest increase in the local share of men raised the rate of marital births by 9.7 percent, up from a base average of 47 marital births per 1,000 women. At the same time, the rate of non-marital births fell by 11.2 percent from a base of 34.4 births per 1,000 women. The likelihood of a woman being married when she gave birth rose by nearly 3 percentage points, while births with unidentified fathers dropped by about 1.5 percentage points.
Maternal health also improved in dating markets with more available men. The share of mothers diagnosed with chlamydia during pregnancy fell by 13 percent relative to the baseline average of 1.9 percent, while maternal hypertension dropped by 17 percent from a baseline average of 2.2 percent. Other conditions, such as diabetes and syphilis, moved in a similar direction, but the results were not statistically significant.
These health benefits extended to newborns in communities with more favorable dating markets for women. The likelihood of a newborn receiving a low APGAR score dropped by 8.3 percent compared to the base rate of 2.4 percent. The APGAR score is a quick observational test given immediately after birth to evaluate a baby’s physical condition, measuring signs like heart rate and breathing, where a low score indicates a need for medical assistance.
The author suggests that these improvements stem from shifts in relational leverage and decision-making power. When women have more potential partners to choose from, their position within relationships strengthens.
“I believe that the underlying logic is about bargaining power,” Zaremba added. “When alternatives exist, what economists call outside options, you have more leverage in a relationship, because you could switch partners. That leverage translates into better treatment, better relationships, and ultimately better health outcomes.”
Through statistical simulations, Zaremba estimated how much of the racial health gap could be tied to partner availability. The models suggest that if Black and White women faced the same local sex ratios, the differences in maternal and infant health outcomes between the two groups would shrink by 5 to 10 percent.
“The effects are small but non-negligible,” Zaremba explained regarding the magnitude of these findings. “The gap in the proportion of men between the Black and White populations is about 5 percentage points. My estimates imply that if the Black population did not have these ‘missing men,’ the gap between Black and White women in marriage rates among those giving birth would shrink by 3.8%, and the gap in chlamydia prevalence would decline by 6%. Partner availability is a rarely discussed mechanism behind these inequalities, but the research shows it matters and might explain part of them.”
The study relies on a specific slice of the American population to draw its conclusions. Because the research leverages random birth fluctuations in smaller communities, the findings are most applicable to people living in small to mid-sized, less urban counties. The results may not apply to individuals in highly mobile populations or those living in massive metropolitan centers where dating markets function differently.
The findings also depend on the assumption that individuals mostly date within their own race, age group, and county. If people frequently travel long distances to find partners or regularly date across racial and age boundaries, the local county sex ratios would have less of an impact on their romantic prospects.
Zaremba emphasized that his work should not be misconstrued as an evaluation of criminal justice policy or personal advice. “The study doesn’t tell us what would happen if we changed incarceration laws to bring more men back into these communities,” Zaremba noted. “That would involve a specific population and many other effects my study doesn’t capture; I’m looking at purely random variation in the supply of available men.”
He also noted that the research is purely observational regarding market dynamics. “The study also doesn’t offer any dating advice,” he clarified. “It simply describes what happens in equilibrium when a market becomes more favorable to women: their marriage and health outcomes improve.”
Future research could explore how women adapt to restricted dating markets and how household decisions are made. “I want to better understand the mechanisms and the strategies people use,” Zaremba said regarding his next steps. “Does a stronger market position mean women find better partners, or does it give them more say within the household, over how income is spent, or who works? Or does it make them more selective about whether to have a child at all, for instance through contraception or abortion use?”
The researcher also plans to look at behavioral responses and effects on men. “I’m also interested in how people respond to unfavorable markets: do they migrate, or change the type of partner they look for?” he added. “And there are open questions about the other side of the market: what are the effects on men, and what are the mental health consequences of dating markets more broadly?”
Understanding these broad social factors offers a different perspective on public health interventions. “The determinants of health are varied; it’s not just about hospitals and clinics,” Zaremba emphasized. “Health is also shaped by the social and demographic composition of the communities we live in. Recognizing that gives us a new set of tools for thinking about how to improve health and reduce disparities.”
The study, “The Effect of Dating Markets on Maternal and Neonatal Health,” was authored by Krzysztof Zaremba.