Research suggests that the outcomes of major soccer tournaments, like the World Cup, might influence the sexual behavior of fans, leading to measurable changes in local birth rates and daily intimate experiences.
While some studies provide evidence that exciting victories inspire celebratory intimacy that boosts birth rates, other research indicates that unexpected losses or the sheer time spent watching games can suppress reproductive behavior. These findings highlight how broad cultural events and the collective emotions they generate might subtly shape population demographics and personal relationships.
To understand how a soccer game might affect birth rates, it helps to look at the psychological and biological theories connecting emotions to reproductive behavior. One popular idea is the concept of celebratory intercourse. This theory suggests that the excitement and happiness following a major sports victory cause hormonal changes that increase sexual desire. When a team wins, the shared euphoria and festive environments might lower inhibitions and lead to more sexual activity.
Research suggests that watching a favorite team win can temporarily elevate testosterone levels in fans. This hormonal surge is thought to be tied to feelings of dominance and victory, which can translate into an increased drive for physical intimacy. On the other hand, researchers also propose the idea of sorrowful abstention. When a deeply supported team loses, fans often experience negative emotions like sadness, stress, and frustration.
These negative feelings tend to reduce sexual desire and the likelihood of physical intimacy. Watching a team fail is known to increase levels of cortisol, a hormone associated with stress and anxiety. Elevated cortisol can suppress reproductive hormones, leading to a temporary disinterest in sexual activity. As a result, unexpected sports losses might lead to a temporary drop in conception rates among the fan base.
Another important background concept is the human sex ratio at birth. This ratio compares the number of male babies born to the number of female babies born. Biologically, this ratio tends to hover around a slight excess of male births. However, environmental stressors can influence this biological balance over time.
The Trivers-Willard hypothesis is an evolutionary theory that attempts to explain this shifting ratio phenomenon. According to this hypothesis, female mammals have evolved a subtle biological ability to adjust the sex of their offspring based on environmental conditions. In times of extreme stress or hardship, pregnant women might be more likely to spontaneously miscarry frail male fetuses early in pregnancy. This biological mechanism favors the birth of hardier female offspring during difficult times.
In contrast, under positive and low-stress conditions, carrying male offspring to term becomes much more likely. Because passionate sports fans experience real stress when their team performs poorly, researchers suspect that major sports failures could temporarily alter the local sex ratio at birth. Psychological theories also play a role in explaining how sports affect human reproductive behavior. Prospect theory is a behavioral economics concept that explains how people make decisions based on perceived gains and losses.
A key part of prospect theory is the idea of loss aversion. Loss aversion suggests that the psychological pain of losing is significantly stronger than the joy of an equivalent win. If fans expect their team to win and they lose, the resulting negative mood shock is theoretically much larger than the positive mood shock of an expected victory. Social identity theory helps explain why fans care so much about sports in the first place.
This theory proposes that a person’s sense of who they are is heavily based on the groups they belong to. For many people, supporting a national or local soccer team is a major part of their social identity. When the team performs well, the fans experience a boost in self-esteem. When the team fails, the fans feel a personal sense of failure, which can easily spill over into their private lives and relationships.
A large study analyzed the long-term relationship between national soccer team success and birth rates across Europe. The researchers wanted to see if the euphoria generated by sports success actually increased human conception, as is often suggested by popular media. They gathered monthly birth data from fifty European countries covering a span of fifty-six years, from 1960 to 2016. The sample included over seventeen thousand observations of monthly birth rates at the country level.
To measure the success of the national teams, the researchers used a standard sports ranking metric known as the ELO rating system. This system assigns points based on match results, the importance of the match, and the strength of the opposing team. It also cumulates points over the course of the tournament, rewarding teams that advance deeper into the competition. The researchers specifically looked at twenty-seven major international sporting events.
These events included fourteen World Cups and thirteen European Championships. The researchers used statistical models to compare the team performance scores against the number of births nine months after the tournaments took place. They controlled for various factors, including the season of the year and whether the country was acting as the host of the tournament. The models were designed to isolate the specific impact of the team’s performance on the conception rates during the month of the tournament.
The study was published in the journal Economics Letters. The findings contradicted the popular narrative of sports-induced baby booms. The researchers found that an increase in a national team’s performance was associated with a drop in birth rates nine months later. Specifically, an average performance score resulted in a birth rate drop of about 0.3 percent.
While this percentage seems small, it translates to thousands of fewer babies born across large nations like France or Italy. The authors proposed a time-allocation theory to explain these surprising findings. They suggested that watching live soccer matches takes time away from physical intimacy. Because major tournaments feature unique matches that demand collective attention, fans spend their evenings glued to television screens or celebrating in public spaces.
This public engagement displaces the private time necessary for reproduction, leading to fewer conceptions during the tournament month. The researchers provided evidence that this shift in time management overrides any potential boosts in fertility caused by post-game euphoria. In the end, simply participating heavily in watching the tournament acts as a slight damper on reproductive activity.
Another study examined how the World Cup affected the sex ratio of babies born in the Mediterranean nation of Malta. Malta has a unique cultural relationship with soccer. Because the country is small, its national team rarely competes at the highest international levels. Due to historical and political reasons, Maltese fans tend to passionately support the national teams of either Italy or England.
The researcher collected data on all live births in Malta from 1958 to 2013, which included a total of 297,254 babies. The analysis focused specifically on the months when the World Cup is traditionally held. The researcher calculated the male-to-female ratio for the births occurring exactly eight to nine months after these tournaments. The goal was to see if the emotional highs and lows of the tournament altered the biological sex balance of the newborns.
To determine this, the researcher compared the sex ratio of babies born in the February following a World Cup to the ratio in all other months and years. The analysis relied on historical government demographic data to track these long-term trends accurately. The study was published in the British Journal of Medicine and Medical Research.
The analysis revealed a statistically significant drop in the proportion of male babies born in the February following a World Cup. During normal periods, the male-to-female ratio hovered around the expected biological average. Following the World Cup, the ratio skewed heavily toward female babies. This drop was unique to the months immediately following the tournament and did not appear as a regular seasonal variation.
The researcher provided evidence that this shift might be linked to the extreme stress experienced by passionate fans. According to the Trivers-Willard hypothesis, the stress of watching favored teams struggle or fail could lead to a higher rate of spontaneous miscarriage of male fetuses early in pregnancy. In addition, the researcher noted that the intense focus on television screens might have lowered overall coital frequency among the population. Lower frequencies of intercourse are biologically associated with a higher likelihood of female conceptions, which could further explain the shifting birth ratios.
To synthesize the conflicting evidence surrounding sports and birth rates, a team of researchers conducted a systematic review. A systematic review is a type of study that collects and analyzes all the previous research published on a specific topic. The researchers searched major scientific databases for any studies that tracked birth rates or sex ratios exactly nine months after a major sporting event. They followed established guidelines for systematic reviews to ensure their search was comprehensive and objective.
The researchers identified ten distinct articles that met their strict criteria for inclusion. These articles covered a variety of sports, including American football, soccer, and rugby. The tournaments analyzed spanned multiple continents, including North America, Europe, Africa, and Asia. The review was published in the journal PeerJ.
The review found that several major tournaments were indeed linked to noticeable increases in birth metrics. For example, the 2010 World Cup in South Africa was followed by over one thousand extra births and an increased male-to-female sex ratio nine months later. A similar baby boom occurred in certain Spanish provinces nine months after a popular soccer club won a major European championship in 2009. The researchers also noted an increase in births in Northern Ireland following their participation in the 2016 European championship.
The researchers noted that the context of the tournament was highly important to the outcome. Baby booms were most likely to happen when a country hosted a major event for the first time or when a national team achieved an unexpected, historic victory. In these specific contexts, the intense collective euphoria seems to trigger an increase in celebratory intimacy. On the other hand, the review also confirmed that unexpected losses by popular teams were linked to a decline in local births nine months later.
A fourth study looked closely at how unexpected soccer outcomes influence birth rates in Spain. The researchers wanted to test the concept of prospect theory, which suggests that people react more strongly to unexpected losses than to unexpected wins. They hypothesized that the negative mood shock of a surprising defeat would suppress fertility more than a surprising victory would boost it.
To measure expected versus unexpected outcomes, the researchers used historical betting odds. Betting markets are generally very accurate at aggregating public expectations about a sports match. The researchers gathered data on every game played in the top Spanish soccer league from the 2000 to 2015 seasons. They compared the betting odds before the game to the actual final scores to identify matches that ended in surprising upsets or unexpected victories.
The researchers then paired these match results with the monthly birth records for every province in Spain. They focused on the performance of the most popular local team in each province. The statistical models looked for changes in the birth rate exactly nine months after a month filled with expected or unexpected match results. The study was published in the European Journal of Population.
The results provided strong evidence for the prospect theory hypothesis. The researchers found that an unexpected loss by a local team led to a 0.8 percent decrease in the number of births in that province nine months later. In a large province, this equates to roughly fifty fewer babies born due to a single unexpected defeat. As expected by the theory of loss aversion, unexpected wins did not produce a corresponding increase in births.
The researchers ran several additional tests to confirm their findings. They found that the drop in births was even more pronounced following extreme upsets, where the team was heavily favored to win but lost anyway. They also found that the effect was strongest in provinces with the highest percentage of passionate soccer fans. These secondary tests provided evidence that short-term negative mood shocks caused by sports can temporarily disrupt reproductive behavior.
While previous studies relied on long-term birth records, a recent study tracked the daily sexual behaviors of fans during a tournament. The researchers wanted to see how national team performance affected individual sexual thoughts, feelings, and actions in real time. They organized an event-sampling study during the 2024 European soccer championship. In this type of study, participants fill out short surveys repeatedly over a period of time to capture their daily experiences.
The sample included 952 adult participants from five different European countries. The specific countries involved were England, Germany, Italy, the Netherlands, and Poland. Before the tournament began, the participants reported their baseline levels of sexual thoughts and activities. During the tournament, the participants received a survey the day after their national team played a match.
The participants were asked to report how often they experienced sexual fantasies, felt sexual desire, or engaged in physical intimacy since the game ended. The researchers collected over 3,600 event-related questionnaires throughout the tournament. They used complex statistical models to compare the participants’ sexual behaviors following wins, losses, and ties. They also asked participants to rate their daily life satisfaction and happiness to see if mood changes explained the shifts in behavior.
The study was accepted for publication in the journal Social Psychological and Personality Science. The study revealed that participants experienced significantly more sexual events following a national team victory compared to a loss. Winning all three group-stage matches was associated with a 27 percent increase in sexual events over the following days. The researchers found that this boost applied to sexual thoughts, emotional desires, and physical behaviors alike.
The effect was especially pronounced among individuals who strongly identified as passionate soccer fans. The researchers also discovered that daily well-being acted as a psychological bridge between the game results and sexual behavior. When a team won, the participants reported higher levels of happiness and life satisfaction. This elevated positive mood directly predicted a higher frequency of sexual events.
Surprisingly, the study also found that overall sexual activity was actually higher in the weeks before the tournament than during the tournament itself. This finding suggests that the event as a whole might act as a slight distraction from physical intimacy. However, within the tournament window, positive outcomes still drove an increase in desire and activity compared to negative outcomes.
While these studies provide fascinating insights into human behavior, they share several limitations that require attention. One major limitation of the birth rate studies is a concept called the ecological fallacy. The ecological fallacy occurs when researchers use broad, population-level data to make assumptions about individual behavior. Just because a birth rate drops in a specific province does not guarantee that the most passionate soccer fans are the exact individuals having fewer children.
Another limitation is the observational nature of the data. Because researchers cannot experimentally manipulate the outcome of a World Cup, they must rely on natural occurrences. This means that hidden variables could be influencing both the mood of the population and the local birth rates. For example, a national holiday or a shift in the local economy might coincide with a tournament, subtly skewing the demographic data.
The daily event-sampling study also faces challenges regarding the direction of cause and effect. The researchers assumed that a positive mood caused an increase in sexual desire. It is equally possible that experiencing sexual desire or engaging in physical intimacy caused the participants to report a higher positive mood. Untangling this bidirectional relationship requires highly detailed tracking of emotions and behaviors hour by hour.
Future research could build upon these findings by tracking hormonal changes in fans during major tournaments. By measuring testosterone and cortisol levels before and after matches, scientists might identify the exact biological pathways connecting sports to reproductive behavior. In addition, future studies could expand their focus to different regions of the world to see if cultural attitudes toward sports and intimacy alter these patterns. Investigating other highly emotional public events, such as political elections, could also help determine if these behavioral shifts are universal to all collective emotional experiences.
The study, “More goals, fewer babies? On national team performance and birth rates,” was authored by Luca Fumarco and Francesco Principe.
The study, “The Male: Female Ratio at Birth in Malta is Decreased by the Soccer World Cup,” was authored by Victor Grech.
The study, “Sporting tournaments and changed birth rates 9 months later: a systematic review,” was authored by Gwinyai Masukume, Victor Grech, and Margaret Ryan.
The study, “Soccer Scores, Short-Term Mood and Fertility,” was authored by Fabrizio Bernardi and Marco Cozzani.
The study, “A Kick to Desire: National Teams’ Performance during the UEFA EURO 2024 Affected the Frequency with Which Europeans Experienced Sexual Events,” was authored by Marcel Weber, Malte Friese, Yannik A. Escher, Hannes M. Petrowsky, Lea Boecker, Kathi Diel, Paweł Muniak, Meikel Neumann, Danna Oomen, Annik Strauch, Oliver Genschow, and David D. Loschelder.
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