Excitement surrounding big sports tournaments like the Super Bowl or the World Cup might lead to more than just team spirit; a scientific review published in PeerJ indicates these events could be linked to a bump in birth rates roughly nine months later. Researchers found that major sporting tournaments appear to have a noticeable influence on birth patterns, affecting both the number of births and the ratio of male to female babies born. This effect is likely driven by the intense emotions stirred up by these events.
Previous research has documented birth rate fluctuations following significant social events. Holidays such as Christmas and New Year’s Eve have been associated with increased conception rates due to a combination of festive mood, alcohol consumption, and time off work. Similarly, researchers have noted potential baby booms after major cultural festivals. However, the relationship between sporting events and birth patterns has remained less explored, despite anecdotal claims and isolated studies suggesting a link.
Sports hold a special place in global culture, with tournaments like the FIFA World Cup, the Super Bowl, and the Olympic Games drawing billions of viewers. These events generate intense emotions, fostering national unity and shared excitement, especially when a team achieves a historic victory. Given the widespread passion for sports, researchers suspected that such tournaments might trigger behavioral changes at the population level, particularly regarding intimate relationships.
Additionally, studies have found that emotions tied to sports can influence hormones such as testosterone and cortisol, which play roles in human reproductive behavior. By examining whether birth rates change following major sporting events, the researchers aimed to determine whether these competitions contribute to larger demographic shifts.
The researchers conducted a systematic review, a rigorous method for comprehensively gathering and analyzing all available research on a specific topic. They began by defining clear criteria for the studies they would include. Eligible studies had to be ecological in nature (meaning they looked at population-level data rather than individual data), examine the impact of a major sporting tournament (either directly attending or watching on media), and compare birth rates or sex ratios about nine months after the event to those of control periods (usually the same time of year in previous or subsequent years).
Using a predefined search strategy, they searched two major scientific databases, PubMed and Scopus, for relevant articles published up to November 7, 2022. They also manually searched the reference lists of included studies and used Google Scholar to identify any articles that cited these studies. Two researchers independently screened the titles and abstracts of the identified articles, then reviewed the full text of potentially relevant studies to determine their eligibility. Any disagreements were resolved through discussion. They did not limit their search by language, date, or publication type (with a few exceptions, like reviews and editorials).
From an initial pool of over 400 articles, 10 studies met the inclusion criteria. The researchers extracted data from these studies, including the type of sporting event, the location, the time period, and the observed changes in birth rates or sex ratios. Because the studies covered a wide range of sports, locations, and time periods, the researchers performed a narrative synthesis, summarizing the findings in a descriptive manner.
The review found that several major sporting tournaments were associated with changes in birth patterns approximately nine months later. These changes primarily involved increases in either the total number of births, the sex ratio at birth (the proportion of male births to total births), or both.
Super Bowl: While one study found no overall increase in births in winning counties after the Super Bowl, another study showed a consistent increase in the sex ratio at birth in the United States nine months after several Super Bowls.
2009 UEFA Champions League: Nine months after Futbol Club Barcelona’s victory, there was a substantial 16% increase in births in certain regions of Catalonia, Spain.
2010 FIFA World Cup: In South Africa, which hosted the tournament for the first time, there was an increase in both the sex ratio at birth and the total number of births (over 1,000 extra births) nine months later.
2016 UEFA European Championship: Nine months following Northern Ireland’s first-time participation in this soccer tournament, in which they advanced to the knockout stage, Northern Ireland experienced a 2% rise in births.
2019 Rugby World Cup: Hosting this tournament for the first time, Japan saw an increase in the sex ratio at birth in some prefectures ten months later.
Spanish La Liga: There was evidence that unexpected losses by popular soccer teams in Spain’s top league were associated with a 0.8% decrease in births in the corresponding provinces nine months later. Unexpected victories, in constrast, showed no correlation with altered birth rates.
The review authors put forward a potential explanation for these findings, noting that the context of the sporting event appeared to be important. Baby booms were more likely when a country hosted a major tournament for the first time or when a team achieved an unexpected victory or a significant milestone (like qualifying for a tournament for the first time). These situations likely generate heightened excitement and positive emotions, which could lead to increased sexual activity and conceptions. The emotional highs of the tournament may trigger hormonal shifts that encourage more sexual activity, leading to more babies nine months later.
The study, “Sporting tournaments and changed birth rates 9 months later: a systematic review,” was authored by Gwinyai Masukume, Victor Grech, and Margaret Ryan.