The Economics of Maternal Stress, Why Studying the Super Bowl Simplifies the Equation
Mansour and other CU Economists Use Large Datasets to Isolate an Important Variable in Infant Health Outcomes
Hani Mansour, Associate Professor in the Department of Economics, understands why his research topics surprise people. He says, "It always surprises non-economists that economists are interested in topics like infant health and stress. But it's actually a really big field; a lot of people are interested in different aspects that affect fetal health, mainly because there is a growing body of evidence showing that poor fetal health is associated with adverse long-term economic outcomes." The ability to quantitatively analyze varied aspects of human behavior is where economists thrive, Mansour asserts, and it's exactly what attracted Mansour to economics in the first place.
Mansour spent the summer presenting findings and preparing a paper (currently submitted) on the effects of maternal stress on birth outcomes. "On average, children who are born with, let's say, low birth weight have worse educational and labor market outcomes. The effects of such early life events don't just disappear," says Mansour. "Of course, many factors can impact fetal health. For example, previous studies focused on exposure to air pollution. Other studies analyzed the impacts of poverty, which involve big issues like nutrition, access to health care, etcetera. And one of the issues that is related to all this but very hard to study is the impact of maternal stress."
Mansour clarifies that the reason it's hard to study is that experimentally there's no way you can expose some pregnant women to stress and others not—it's the same reason why the impacts of maternal smoking or drinking cannot be studied in a lab setting. He says, "You have to find contexts in real life, or what we call natural experiments, that allow you to identify the causal effects of maternal stress. Which is obviously something that is very common; it's something that a lot of women experience."
Maternal stress is associated with many other factors that could also influence fetal health, but proving a causal relationship of maternal stress is very difficult. To overcome this challenge, previous studies have used dramatic events like death in families or earthquakes and hurricanes to evaluate the impacts of major stress events on expectant mothers and fetal development. Mansour says that these studies provide valuable evidence about the impacts of exposure to stress. He himself published a piece in the Journal of Development Economics in 2012, with Professor Daniel Rees, that focused on exposure to armed conflict and birth weight during the Second Intifada in the West Bank region. But he says, "The problem with isolating the impact of stress during armed conflicts is that conflicts are also likely to affect other factors, such as access to health care and nutrition." Moreover, Mansour acknowledges that the stress that women in Palestine were exposed to is difficult to compare to the stress of day-to-day life in America, and so studying the effects of a more common-place and low-intensity stressor on birth weight is particularly important for mothers here.
Enter the Super Bowl. Mansour, along with Rees and Professor Brian Duncan, started studying the impact of the exposure to the Super Bowl on birth weight. Mansour stresses that "This is NOT a paper ABOUT the Super Bowl. What the Super Bowl provides is an opportunity to understand the impact of a low stress event on birth outcomes, since although major sporting events elicit intense emotions they do not threaten viewers with direct physical harm or limit access to prenatal care."
A key feature that makes the Super Bowl interesting is that predicting which teams will make it to the final game in a given year is hard, and for the purpose of study is essentially randomly determined. As a result, Mansour and collogues could compare the birth outcomes of women who happened to be pregnant when the team from their town made it to the Super Bowl to pregnant women who lived in the same areas in years when the local team did not make it to the final game. The stress can be experienced from watching the game itself, or because of other related factors such as traffic and parades, vandalism and rioting, changes in spousal relations and moods, or even simple schedule and pattern disruptions. Mansour adds, "Although many other behaviors, such as smoking and drinking might mediate the relationship between stress and birth weight, the results provide strong evidence that stress is, at a minimum, the first step along the causal pathway."
Data on over twelve million live births, available from the U.S. Vital Statistics, on the population of the cities competing in the Super Bowl spanning the years 1969-2004 were compared to data on the same populations in years when their team is not competing in the Super Bowl. The point was not to compare the data of the towns with the winning and the losing team from a single year, but rather, as Mansour cites as an example, "To compare data from Phoenix in a Super Bowl year, and data from Phoenix in a non-Super Bowl year."
Mansour and colleagues went into the project thinking it was high risk, and that there was a great probability they might finding nothing. They were surprised to discover that exposure to the Super Bowl was in fact associated with a higher likelihood of having a low birth weight child. Digging in deeper Mansour and the team looked at whether winning or losing the Super Bowl has different effects. They found that winning the Super Bowl is associated with a higher likelihood of lower birthweight outcomes than losing. Observes Mansour, "We always associate stress with something negative, but actually losses don't seem to have that much of an impact in the Super Bowl context." The researchers also used the Las Vegas point spread to classify game outcomes as expected versus unexpected and found that unexpected wins had the largest negative impact on birth weight.
Mansour speculates that after a loss, "If you think about what happened around here when Denver lost the Super Bowl, what happens the next day? Everyone is just avoiding the conversation; no one wants to talk about it. And there are no parades. There are no parties, and no vandalism."
When the paper is published in the coming months, Mansour will continue to field questions about why someone with an Economics PhD would study topics like stress and birth weight rather than, say, the economic development of the winning or losing city itself. The widely held belief that economists evaluate the cost of vandalism or the benefit in sales of merchandise after a major sporting event, not the impact on local health issues, is one that Mansour is familiar with. He says, "I really like the perspective that economics provides, and the statistical tools that it gives us. The Super Bowl provides a great natural experiment as it randomizes pregnant women into treatment and control groups, even if I don't have a lab."
Mansour's previous research into marriage "markets" (with CU Boulder Professor Terra McKinnish) might sound like more traditional ground for an economist—until you dig deeper. Mansour and McKinnish got interested in the cultural phenomena of the "cougar" classification of older women seeking out and marrying younger men, and decided to take a closer look. One of the four resulting papers "Who Marries Differently-Aged Spouses? Ability, Education, Occupation, Earnings and Appearance," published in the Review of Economics and Statistics in 2014, documented that couples who had a large age gap are on average less attractive and successful than couples who married a partner closer to their own age, which is contrary to conventional wisdom. The paper points to the importance of social networks which one encounters early in life (through work or college) as an important determinant of who an individual marries.
"Of course economists study family dynamics and family formation, of course!" Mansour says. "Family formation and dissolution are some of the most basic and consequential decisions people make in their lives." Mansour sees the discipline of economics as a theoretical framework that has particular value in studying human behavior. Economists are also uniquely trained in conceptualizing how to analyze such behaviors empirically using sophisticated empirical methods and large data sets. He encourages any student with a curious mind to look into economics as a way to develop the critical thinking skills that many modern problems require, and many employers seek out.