Stress and fertility decisions: Evidence from a home team’s championship victory

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If this is the case, it is likely that women tend to avoid pregnancy during times of stressful events. We examined this hypothesis using a baseball home team’s championship victory when people likely gather and make a noise, which could affect emotions and stress levels. Data were taken from South Korea, where baseball is the most popular professional sport. As the championship team region changed yearly, we employed a difference-in-differences estimation method. We found that a home team’s championship win did not change the overall birth rate nine months later. However, the birth rate among women with college degrees decreased by 4.7%, while the birth rate among those without degrees remained unaffected. JEL Classifications: D91; I10: J13; Z20 sports event stress fertility birth rate 1. Introduction The literature shows that in-utero maternal stress significantly affects offspring’s health. For example, birth weight decreases due to stress induced by maternal bereavement (Black, Devereux, and Salvanes, 2016 ); terrorist attack (Brown, 2020 ); war (Mansour and Rees, 2012 ); and natural disasters (Currie and Rossin-Slater, 2013 ; Kim, Carruthers, and Harris, 2017 ; de Oliveira, Lee, and Quintana-Domeque, 2021 ). When maternal stress has negative impact on offspring’s health, it is likely that women tend to avoid pregnancy during times of stressful events. This study considered a baseball home team’s championship victory as a stressful event to those intending to get pregnant, and examined its effect on fertility decisions. As literature indicates, during a home team’s championship win people likely gather and make a noise, which could affect emotions and stress levels. For example, Lindo, Swensen, and Waddell ( 2012 ) found evidence of increased gathering in response to a win of one’s school football team, and Stoecker, Sanders, and Barreca ( 2016 ) reported a similar evidence in response to having a local team in the Super Bowl. The data came from South Korea, providing an ideal setting for performing this analysis because baseball is the most popular professional sport, and the fact that the championship team’s region changed yearly allowed us to employ a difference-in-differences estimation method. Additionally, the country has recorded the lowest fertility rate in the world. The total fertility rate was 0.78 in 2022 and 1.23 in 2010, suggesting that many women have only one or no children in their lives. Therefore, their fertility decisions could be more susceptible to the occurrence of stressful events compared to those of women in high-fertility countries. In other words, women in low-fertility countries might be more concerned about birth outcomes, and some may give up or delay their pregnancies when faced with stressful events. It is worth noting that the literature reports the possibility of increased births driven by celebratory sex after home team wins. For instance, Dilmaghani and Hu ( 2024 ) examined the National Hockey League, and found that exposure to an unexpected win leads to higher fertilities. While the possibility of this is unlikely to be high in a low-fertility country like South Korea, we cannot entirely rule it out in our case. Our study contributes to the literature in the following ways. First, it adds to studies on the effects of stressful events. As described previously, existing studies analyzed the impact of in-utero maternal stress on offspring’s health. However, few have examined fertility decisions immediately after stressful events, although some have explored stressful events that occurred during pregnancy (e.g., de Oliveira, Lee, and Quintana-Domeque, 2021 ) or fertility long after such events (e.g., Nobles, Frankenberg, and Thomas, 2015 ; Nandi, Mazumdar, and Behrman, 2018 ). Second, our study contributes to broader literature on fertility decisions which mostly examines the effect of income or financial incentives (e.g. Tudor, 2020 ; Anelli and Balbo, 2021 ; Gehrke and Kubitza, 2021 ; Brehm and Brehm, 2022 ; Gallego and Lafortune, 2023 ; González and Trommlerová, 2023 ). For example, González and Trommlerová ( 2023 ) reported that the introduction of a universal child benefit in Spain increased birth rates by 3%, and the cancellation led to a 6% decrease. Finally, it adds to the literature on the effect of sports team performance. An example of such studies is Card and Dahl ( 2011 ), who found that an unexpected Super Bowl loss increases domestic violence by a male partner. In addition, Duncan, Mansour, and Rees ( 2017 ) examined children who were conceived before the Super Bowl and found that first-trimester exposure to a Super Bowl win increases the probability of having a child with low birth weight by 4%. These studies differ from ours in that they examine the effects on the behavior of fans, but our study does not necessarily focus on the behavior of fans. The findings are as follows. A home team’s championship win did not affect the overall birth rate nine months later. However, among women with college degrees, the birth rate decreased by 4.7%, while the birth rate of those without degrees remained unaffected. A home team’s championship win and the resultant circumstances could cause stress, leading some women to avoid pregnancy. The divergent results suggest that the avoidance was stronger for women with college degrees, possibly because highly educated women were more likely to be aware of the adverse effects of stress on infant health. The remainder of this paper is organized as follows. Section 2 provides background on the Korean professional baseball league; Section 3 outlines the empirical strategy; Section 4 describes the data; Section 5 presents the results, and Section 6 concludes. 2. Korean Professional Baseball League The Korean Baseball Organization (KBO) league is the most popular professional sports event in the country. 2 Established in 1982 with six teams, the league has since expanded to ten teams. Fourteen out of sixteen regions in the country have their home teams, with each team having one or more regions as their home regions. Games are played each day from Tuesday to Sunday, with each team facing the same opponent for three consecutive games. For our analysis, we focused on the five seasons from 2008 to 2012. These years were selected because, unlike other periods, they featured multiple teams winning championships, and the number of teams in the league remained constant throughout. After 2012, the league saw further expansion with the establishment of two new teams, one in 2013 and another in 2015. As presented in Table A1 , during the five seasons, eight teams competed, and three teams simultaneously won both the regular and the post-season with no other team winning either. The three winning teams are the Wyverns, whose home-region is indicated as No.1 in Figure A1 , Tigers (Nos. 7, 8, and 9), and Lions (Nos. 12 and 13). The Wyverns won in 2008 and 2010, the Tigers won in 2009, and the Lions won in 2011 and 2012. Although the regular season officially ended between September 26 and October 6 in the five seasons, the winning team was determined earlier around September 21–October 1. Furthermore, the post-season began immediately after the regular season ended and ended around October 19–November 1. [2] Our baseball data were collected from the KBO, which oversees the league and maintains all statistics, including team standings. The data can be downloaded from https://www.koreabaseball.com/Kbo/Board/Ebook/EbookPublication.aspx (published in Korean). 3. Empirical Strategy For the estimations, we utilized region/year-month level data aggregated from the individual-level data of approximately 2 million women in the 14 regions with a professional baseball team who gave birth from January to November of 2009–2013. In Eq. (1), the number of observations is 770 (= 14 regions × 5 years × 11 months), and the subscripts r , t , m , and y represent the region, year/month, calendar month, and calendar year, respectively. ln( A rt ) = α 0 + \(\:\sum\:_{j=4}^{14}{\beta\:}_{j}{win}_{rt-j}\) + X rt B + γ r + υ m + δ y + ε rt (1) The dependent variable is the natural log of birth rate. Birth rate is defined as the number of births in a region/year-month divided by the number of days in the month, which is further divided by the region/year-month population, 3 and then multiplied by 100,000; hence, it is the average daily number of newborns per 100,000 residents. For the variable win , mothers have a value of 1 if their home team won the championship 4–14 months before. For example, because Wyverns won the championship in the 2008 and 2010 seasons, those who gave birth in the Wyverns-based region in January–November of 2009 and 2011, have a value of 1. The vector X includes maternal education level and maternal age. In the equation, γ , υ , δ , and ε are the region-, month-, year-fixed effects, and the error term, respectively. 4 The parameters of interest are betas, indicating the effect of a home team’s championship win on the birth rate among women residing in the winning region, presented in percentage form. We anticipate a negative estimate for the birth rate in June (i.e., nine months after a championship win). [3] Population data can be downloaded from the following website of the Korean government: https://jumin.mois.go.kr/index.jsp [4] We also estimated the equation controlling for year/month fixed effect, but the results did not change. The results are available upon request. 4. Data The birth registry was collected from the National Statistical Office 5 and was based on approximately 2 million women who gave live births in January–November during the 2009–2013 period. Among them, 120,000 were from Wyverns-based region; 212,000 were from Tigers-based regions; and 202,000 were from Lions-based regions. These winning regions accounted for approximately 26% of the sample. As shown in Table 1 , the birth rate was 2.55, indicating that, on average, 2.55 children per 100,000 residents were born each day. Additionally, 69% of women had a college degree, and the average age was 31. Table 1 Descriptive statistics Mean (1) Standard deviations (2) Birth rate 2.55 0.29 Women with college degrees (%) 69.3 0.07 Age 30.9 0.56 Number of observations 770 The descriptive statistics is from the birth registry and is based on approximately 2 million women who gave birth from January to November of 2009–2013. The birth rate is as outlined in the Empirical Strategy section. The observations of 770 are derived from 14 regions × 5 years × 11 months. [5] The data can be downloaded at https://mdis.kostat.go.kr 5. Results 5.1. Main analysis Table 2 presents the regression results. A home team’s championship win did not affect the overall birth rate nine months later; the coefficient is − 0.16, and is insignificant. However, when we conducted separate analyses based on educaion level, we found a significant effect among those with a college degree. Specifically, thier birth rate nine months after a home team’s championship win decreased by 4.7%. No significant effects ten or more months after the event could imply that the victory had no impact during these months. However, it is also possible that this lack of significance is due to delayed pregnancies coinciding with the continued effects of the win. In other words, delayed pregnancies might increase the birth rate, whereas the continued effects could decrease it, potentially resulting in no significant effect. Table 2 The effect of a home team’s championship win on birth rates 4–14 months after Dependent variable = log of birth rate Months after a championship win 4 5 6 7 8 9 10 11 12 13 14 A: All 0.007 0.011 0.003 0.021 0.009 −0.016 0.017 0.002 −0.000 0.013 −0.005 (0.018) (0.013) (0.008) (0.011) (0.011) (0.012) (0.017) (0.011) (0.013) (0.018) (0.019) B: With college degrees −0.009 0.012 −0.002 0.014 0.004 −0.047* −0.002 −0.007 −0.002 0.000 −0.014 (0.018) (0.014) (0.012) (0.012) (0.014) (0.016) (0.017) (0.015) (0.017) (0.019) (0.023) C: Without college degrees 0.019 −0.013 0.004 0.022 0.008 0.020 0.034 0.012 −0.003 0.027 0.000 (0.024) (0.020) (0.015) (0.021) (0.016) (0.025) (0.028) (0.017) (0.021) (0.023) (0.020) Standard errors are in parentheses and are clustered at the region/year level. The regression also includes a constant, the proportion of those with college degrees, the average age, region-, year-, and month-fixed effect. The population is used as the weight. The number of observations is 770 in each regression, with adjusted R 2 values of 0.89, 0.90, and 0.97, respectively. *: p < 0.05 For women without a college degree, the coefficients are 0.020 nine months after the event and 0.034 ten months after. However, none of the coefficients are significant, suggesting that the avoidance of pregnancy during a home team’s championship win was not substantial. 5.2. Placebo tests Table 2 reveals that birth rates among those with a college degree eight or seven months after a home team’s championship win were unaffected. This implies that the significant effect nine months after was not driven by an event that occurred before September of the previous year. As a placebo test, we assumed that each team won their championship one year earlier. For example, Tigers that won a championship in 2009 were assumed to have won in 2008. This test was conducted using the 2009–2012 data, and in panel A of Table 3 , no significant effects were found. We also assumed that each team won championship one year later than the actual year. This test was conducted using the 2010–2013 data, and panel B of Table 3 shows no significant effects. These results imply that reduced birth rate in June (i.e., nine months after a championship win) among those with a college degree (Table 2 ) does not occur every June but specific to the June of the following year after a championship win. Table 3 Placebo test (those with college degrees only) Dependent variable = log of birth rate Months after a championship win 4 5 6 7 8 9 10 11 12 13 14 A: Victory one year earlier 0.020 0.027 0.001 0.018 0.009 −0.016 −0.003 0.016 −0.016 −0.026 −0.017 (0.030) (0.022) (0.016) (0.014) (0.012) (0.016) (0.013) (0.014) (0.013) (0.022) (0.020) B: Victory one year later 0.027 −0.008 −0.015 0.007 −0.005 −0.023 0.010 −0.020 −0.024 −0.008 −0.040 (0.032) (0.022) (0.017) (0.015) (0.020) (0.021) (0.019) (0.015) (0.014) (0.023) (0.024) Panel A and B assume that each team won their championship one year earlier or later than the actual year, using the 2009–2012 data and 2010–2013 data, respectively. Standard errors are in parentheses and are clustered at the region/year level. Other control variables are the same as in Table 2 . The population is used as the weight. The number of observations in both panels is 616 (= 14 regions × 4 years × 11 months), with adjusted R 2 values of 0.90 and 0.88, respectively. Table 4: Child care and maternal knowledge based on education level With college degrees (1) Without college degrees (2) P-value A: Child care I spend time playing with my baby. (%) 78.2 (41.3) 71.8 (45.0) 0.00 I know what my baby wants and how (s)he feels. (%) 77.3 (41.9) 71.2 (45.3) 0.00 I show positive and warm interest in my baby. (%) 91.1 (28.4) 86.2 (34.6) 0.00 B: Maternal knowledge Babies in general only understand words which they can speak. (%) 70.5 (45.6) 53.6 (49.9) 0.00 How I raise my baby does not affect her/his intelligence. (%) 88.5 (31.9) 78.7 (41.0) 0.00 Babies’ characteristics does not change easily six months after birth or afterwards. (%) 78.5 (41.1) 67.2 (47.0) 0.00 Maximum number of observations 1,264 585 The information presented in this table is from the Panel Study on Korean Children. Panel A shows the proportion of mothers who chose four or five to five-point likert questions, and panel B displays the proportion of those who knew the correctness of each statement (all three statements are false). Standard deviations are in parentheses. 5.3. Why did we observe significant results only among women with college degrees? The differing results in Table 2 indicate that the avoidance was more pronounced for women with college degrees. One possible explanation is that they were likely to have more knowledge of child-rearing, making them more aware of the potential negative effects on the birth outcomes for their babies conceived during stressful events. This assertion is in line with the findings of studies, including Streatfield, Singarimbun, and Diamond ( 1990 ) and Schellekens ( 2021 ), who reported that better-educated mothers have greater knowledge of immunizations and sanitations, resulting in improved child survival. Additionally, Currie and Moretti ( 2003 ) found that maternal education improves infant health through increased use of prenatal care. To verify the above explanation in Korean context, we examined the Panel Study on Korean Children, which is a government-sponsored study of 2,150 singleton babies born during April–July in 2008. 6 An analysis of the Panel supports the aforementioned explanation. For example, as shown in panel A of Table 4, 78.2% of those with college degrees chose four or five on a five-point Likert question, “I spend time playing with my baby,” whereas the number for those without degrees was 71.8% (p-value = 0.00). In addition, in panel B, 70.5% of those with college degrees knew the correctness of the statement, “Babies in general only understand words which they can speak,” whereas the number for those without degrees was 53.4% (p-value = 0.00). 5.4. Robustness checks We conducted two robustness checks. First, to examine whether the findings among those with a college degree were driven by one or two fan base regions, we excluded one fan base region at a time. When we excluded the regions of the Wyverns, Tigers, and Lions from the analysis, the estimate was 2.6%, 5.6%, and 6.4%, respectively, which implies that all three fan base regions were affected by their home team wins. As another robustness check, we excluded regions with no winning teams and instead included regions with no baseball teams (Nos. 10 and 11 in Figure A1 ) to examine whether the betas in Eq. (1) indicate the effect of not winning (or losing) on the birth rate. We found that the corresponding estimate is 3.9%, which is not significantly different from the estimate obtained in the original analysis. [6] The study collects various information on mothers as well as on the babies, and hence, it is possible to examine maternal behavior and knowledge regarding pregnancy and child-rearing, based on education. The data can be downloaded at https://panel.kicce.re.kr/pskc/index.do 6. Conclusion When in-utero maternal stress has negative impact on offspring’s health, it is likely that women tend to avoid pregnancy during times of stressful events. Although previous studies examined the effect of stressful events that occurred during pregnancy on live births, few have explored pregnancy immediately after stressful events. We investigated this topic using data from a South Korean professional baseball league. We found that a home team’s championship victory reduced the birth rate nine months later among women with college degrees by 4.7%, whereas those without degrees were unaffected. Highly educated women were more likely to be aware of the adverse effects of stress on infant health and, leading them to avoid pregnancy. Although we attributed the decrease in birth rates to the intentional avoidance of pregnancy, it is also possible that these women attempted to become pregnant, but failed due to stress (a biological factor). Additionally, they might have chosen to abort a baby conceived during the championship period due to concerns about birth outcomes. If highly educated women have better access to health care services, including abortion, this could also explain our findings. Declarations Author Contribution Yoonmin Kim wrote Sections 1 and 2, and Hyunkuk Cho wrote the remaining parts. Data Availability doi: 10.17632/n4btc6w4yk.1 References Anelli, M., & Balbo, N. (2021). Fertility drain or fertility gain? Emigration and fertility during the Great Recession in Italy. Demography , 58 (2), 631-654. Black, S. E., Devereux, P. J., & Salvanes, K. G. (2016). Does grief transfer across generations? Bereavements during pregnancy and child outcomes. American Economic Journal: Applied Economics , 8 (1), 193-223. Brehm, M. E., & Brehm, P. A. (2022). Drill, baby, drill: Natural resource shocks and fertility in Indonesia. Labour Economics , 102178. Brown, R. (2020). The intergenerational impact of terror: did the 9/11 tragedy impact the initial human capital of the next generation?. Demography , 57 (4), 1459-1481. Card, D., & Dahl, G. B. (2011). Family violence and football: The effect of unexpected emotional cues on violent behavior. Quarterly Journal of Economics , 126(1), 103-143. Currie, J., & Moretti, E. (2003). Mother’s education and the intergenerational transmission of human capital: Evidence from college openings. Quarterly Journal of conomics , 118 (4), 1495-1532. Currie, J., & Rossin-Slater, M. (2013). Weathering the storm: Hurricanes and birth outcomes. Journal of Health Economics , 32 (3), 487-503. de Oliveira, V. H., Lee, I., & Quintana-Domeque, C. (2021). Natural disasters and early human development: Hurricane Catarina and infant health in Brazil. Journal of Human Resources , 0816-8144R1. Dilmaghani, M., & Hu, M. (2024). Hockey babies: National Hockey League outcomes and short-term fertility spikes in Canada. Sports Economics Review , 6 , 100033. Duncan, B., Mansour, H., & Rees, D. I. (2017). It’s just a game: The Super Bowl and low birth weight. Journal of Human Resources , 52 (4), 946-978. Gallego, F., & Lafortune, J. (2023). Baby commodity booms? The impact of commodity shocks on fertility decisions and outcomes. Journal of Population Economics , 36 (1), 295-320. Gehrke, E., & Kubitza, C. (2021). Agricultural productivity and fertility rates: Evidence from the Oil Palm Boom in Indonesia. Journal of Human Resources , 0520-10905R1. González, L., & Trommlerová, S. K. (2023). Cash transfers and fertility: How the introduction and cancellation of a child benefit affected births and abortions. Journal of Human Resources , 58 (3), 783-818. Kim, B., Carruthers, C. K., & Harris, M. C. (2017). Maternal stress and birth outcomes: Evidence from the 1994 Northridge earthquake. Journal of Economic Behavior & Organization , 140 , 354-373. Lindo, J. M., Swensen, I. D., & Waddell, G. R. (2012). Are big-time sports a threat to student achievement?. American Economic Journal: Applied Economics , 4(4), 254-74. Mansour, H., & Rees, D. I. (2012). Armed conflict and birth weight: Evidence from the al-Aqsa Intifada. Journal of Development Economics , 99 (1), 190-199. Nandi, A., Mazumdar, S., & Behrman, J. R. (2018). The effect of natural disaster on fertility, birth spacing, and child sex ratio: evidence from a major earthquake in India. Journal of Population Economics , 31 , 267-293. Nobles, J., Frankenberg, E., & Thomas, D. (2015). The effects of mortality on fertility: population dynamics after a natural disaster. Demography , 52 (1), 15-38. Schellekens, J. (2021). Maternal education and infant mortality decline. Demographic Research , 45 , 807-824. Stoecker, C., Sanders, N. J., & Barreca, A. (2016). Success is something to sneeze at: Influenza mortality in cities that participate in the Super Bowl. American Journal of Health Economics , 2(1), 125-143. Streatfield, K., Singarimbun, M., & Diamond, I. (1990). Maternal education and child immunization. Demography , 27 , 447-455. Tudor, S. (2020). Financial incentives, fertility and early life child outcomes. Labour Economics , 64 , 101839. Additional Declarations No competing interests reported. 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Introduction","content":"\u003cp\u003eThe literature shows that in-utero maternal stress significantly affects offspring\u0026rsquo;s health. For example, birth weight decreases due to stress induced by maternal bereavement (Black, Devereux, and Salvanes, \u003cspan citationid=\"CR3\" class=\"CitationRef\"\u003e2016\u003c/span\u003e); terrorist attack (Brown, \u003cspan citationid=\"CR8\" class=\"CitationRef\"\u003e2020\u003c/span\u003e); war (Mansour and Rees, \u003cspan citationid=\"CR35\" class=\"CitationRef\"\u003e2012\u003c/span\u003e); and natural disasters (Currie and Rossin-Slater, \u003cspan citationid=\"CR14\" class=\"CitationRef\"\u003e2013\u003c/span\u003e; Kim, Carruthers, and Harris, \u003cspan citationid=\"CR30\" class=\"CitationRef\"\u003e2017\u003c/span\u003e; de Oliveira, Lee, and Quintana-Domeque, \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2021\u003c/span\u003e).\u003c/p\u003e \u003cp\u003eWhen maternal stress has negative impact on offspring\u0026rsquo;s health, it is likely that women tend to avoid pregnancy during times of stressful events. This study considered a baseball home team\u0026rsquo;s championship victory as a stressful event to those intending to get pregnant, and examined its effect on fertility decisions. As literature indicates, during a home team\u0026rsquo;s championship win people likely gather and make a noise, which could affect emotions and stress levels. For example, Lindo, Swensen, and Waddell (\u003cspan citationid=\"CR33\" class=\"CitationRef\"\u003e2012\u003c/span\u003e) found evidence of increased gathering in response to a win of one\u0026rsquo;s school football team, and Stoecker, Sanders, and Barreca (\u003cspan citationid=\"CR44\" class=\"CitationRef\"\u003e2016\u003c/span\u003e) reported a similar evidence in response to having a local team in the Super Bowl.\u003c/p\u003e \u003cp\u003eThe data came from South Korea, providing an ideal setting for performing this analysis because baseball is the most popular professional sport, and the fact that the championship team\u0026rsquo;s region changed yearly allowed us to employ a difference-in-differences estimation method. Additionally, the country has recorded the lowest fertility rate in the world. The total fertility rate was 0.78 in 2022 and 1.23 in 2010, suggesting that many women have only one or no children in their lives. Therefore, their fertility decisions could be more susceptible to the occurrence of stressful events compared to those of women in high-fertility countries. In other words, women in low-fertility countries might be more concerned about birth outcomes, and some may give up or delay their pregnancies when faced with stressful events.\u003c/p\u003e \u003cp\u003eIt is worth noting that the literature reports the possibility of increased births driven by celebratory sex after home team wins. For instance, Dilmaghani and Hu (\u003cspan citationid=\"CR19\" class=\"CitationRef\"\u003e2024\u003c/span\u003e) examined the National Hockey League, and found that exposure to an unexpected win leads to higher fertilities. While the possibility of this is unlikely to be high in a low-fertility country like South Korea, we cannot entirely rule it out in our case.\u003c/p\u003e \u003cp\u003eOur study contributes to the literature in the following ways. First, it adds to studies on the effects of stressful events. As described previously, existing studies analyzed the impact of in-utero maternal stress on offspring\u0026rsquo;s health. However, few have examined fertility decisions immediately after stressful events, although some have explored stressful events that occurred \u003cem\u003eduring\u003c/em\u003e pregnancy (e.g., de Oliveira, Lee, and Quintana-Domeque, \u003cspan citationid=\"CR16\" class=\"CitationRef\"\u003e2021\u003c/span\u003e) or fertility long after such events (e.g., Nobles, Frankenberg, and Thomas, \u003cspan citationid=\"CR40\" class=\"CitationRef\"\u003e2015\u003c/span\u003e; Nandi, Mazumdar, and Behrman, \u003cspan citationid=\"CR37\" class=\"CitationRef\"\u003e2018\u003c/span\u003e). Second, our study contributes to broader literature on fertility decisions which mostly examines the effect of income or financial incentives (e.g. Tudor, \u003cspan citationid=\"CR49\" class=\"CitationRef\"\u003e2020\u003c/span\u003e; Anelli and Balbo, \u003cspan citationid=\"CR1\" class=\"CitationRef\"\u003e2021\u003c/span\u003e; Gehrke and Kubitza, \u003cspan citationid=\"CR25\" class=\"CitationRef\"\u003e2021\u003c/span\u003e; Brehm and Brehm, \u003cspan citationid=\"CR6\" class=\"CitationRef\"\u003e2022\u003c/span\u003e; Gallego and Lafortune, \u003cspan citationid=\"CR23\" class=\"CitationRef\"\u003e2023\u003c/span\u003e; Gonz\u0026aacute;lez and Trommlerov\u0026aacute;, \u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e2023\u003c/span\u003e). For example, Gonz\u0026aacute;lez and Trommlerov\u0026aacute; (\u003cspan citationid=\"CR27\" class=\"CitationRef\"\u003e2023\u003c/span\u003e) reported that the introduction of a universal child benefit in Spain increased birth rates by 3%, and the cancellation led to a 6% decrease. Finally, it adds to the literature on the effect of sports team performance. An example of such studies is Card and Dahl (\u003cspan citationid=\"CR10\" class=\"CitationRef\"\u003e2011\u003c/span\u003e), who found that an unexpected Super Bowl loss increases domestic violence by a male partner. In addition, Duncan, Mansour, and Rees (\u003cspan citationid=\"CR21\" class=\"CitationRef\"\u003e2017\u003c/span\u003e) examined children who were conceived \u003cem\u003ebefore\u003c/em\u003e the Super Bowl and found that first-trimester exposure to a Super Bowl win increases the probability of having a child with low birth weight by 4%. These studies differ from ours in that they examine the effects on the behavior of fans, but our study does not necessarily focus on the behavior of fans.\u003c/p\u003e \u003cp\u003eThe findings are as follows. A home team\u0026rsquo;s championship win did not affect the overall birth rate nine months later. However, among women with college degrees, the birth rate decreased by 4.7%, while the birth rate of those without degrees remained unaffected. A home team\u0026rsquo;s championship win and the resultant circumstances could cause stress, leading some women to avoid pregnancy. The divergent results suggest that the avoidance was stronger for women with college degrees, possibly because highly educated women were more likely to be aware of the adverse effects of stress on infant health.\u003c/p\u003e \u003cp\u003eThe remainder of this paper is organized as follows. Section \u003cspan refid=\"Sec2\" class=\"InternalRef\"\u003e2\u003c/span\u003e provides background on the Korean professional baseball league; Section \u003cspan refid=\"Sec3\" class=\"InternalRef\"\u003e3\u003c/span\u003e outlines the empirical strategy; Section \u003cspan refid=\"Sec4\" class=\"InternalRef\"\u003e4\u003c/span\u003e describes the data; Section \u003cspan refid=\"Sec5\" class=\"InternalRef\"\u003e5\u003c/span\u003e presents the results, and Section \u003cspan refid=\"Sec10\" class=\"InternalRef\"\u003e6\u003c/span\u003e concludes.\u003c/p\u003e"},{"header":"2. Korean Professional Baseball League","content":"\u003cp\u003eThe Korean Baseball Organization (KBO) league is the most popular professional sports event in the country.\u003ca class=\"FNLink\" href=\"#Fn1\" id=\"#FNLinkFn1\"\u003e2\u003c/a\u003e Established in 1982 with six teams, the league has since expanded to ten teams. Fourteen out of sixteen regions in the country have their home teams, with each team having one or more regions as their home regions. Games are played each day from Tuesday to Sunday, with each team facing the same opponent for three consecutive games.\u003c/p\u003e \u003cp\u003eFor our analysis, we focused on the five seasons from 2008 to 2012. These years were selected because, unlike other periods, they featured multiple teams winning championships, and the number of teams in the league remained constant throughout. After 2012, the league saw further expansion with the establishment of two new teams, one in 2013 and another in 2015.\u003c/p\u003e \u003cp\u003eAs presented in Table \u003cspan refid=\"Tab4\" class=\"InternalRef\"\u003eA1\u003c/span\u003e, during the five seasons, eight teams competed, and three teams simultaneously won both the regular and the post-season with no other team winning either. The three winning teams are the Wyverns, whose home-region is indicated as No.1 in Figure \u003cspan refid=\"Fig1\" class=\"InternalRef\"\u003eA1\u003c/span\u003e, Tigers (Nos. 7, 8, and 9), and Lions (Nos. 12 and 13). The Wyverns won in 2008 and 2010, the Tigers won in 2009, and the Lions won in 2011 and 2012.\u003c/p\u003e \u003cp\u003eAlthough the regular season officially ended between September 26 and October 6 in the five seasons, the winning team was determined earlier around September 21\u0026ndash;October 1. Furthermore, the post-season began immediately after the regular season ended and ended around October 19\u0026ndash;November 1.\u003c/p\u003e\n\u003cp\u003e[2] Our baseball data were collected from the KBO, which oversees the league and maintains all statistics, including team standings. The data can be downloaded from https://www.koreabaseball.com/Kbo/Board/Ebook/EbookPublication.aspx (published in Korean).\u003c/p\u003e\n\u003cp\u003e\u003cbr\u003e\u003c/p\u003e"},{"header":"3. Empirical Strategy","content":"\u003cp\u003eFor the estimations, we utilized region/year-month level data aggregated from the individual-level data of approximately 2\u0026nbsp;million women in the 14 regions with a professional baseball team who gave birth from January to November of 2009\u0026ndash;2013. In Eq.\u0026nbsp;(1), the number of observations is 770 (=\u0026thinsp;14 regions \u0026times; 5 years \u0026times; 11 months), and the subscripts \u003cem\u003er\u003c/em\u003e, \u003cem\u003et\u003c/em\u003e, \u003cem\u003em\u003c/em\u003e, and \u003cem\u003ey\u003c/em\u003e represent the region, year/month, calendar month, and calendar year, respectively.\u003c/p\u003e \u003cp\u003eln(\u003cem\u003eA\u003c/em\u003e\u003csub\u003ert\u003c/sub\u003e) \u003cem\u003e= α\u003c/em\u003e\u003csub\u003e\u003cem\u003e0\u003c/em\u003e\u003c/sub\u003e + \u003cspan class=\"InlineEquation\"\u003e\u003cspan class=\"mathinline\"\u003e\\(\\:\\sum\\:_{j=4}^{14}{\\beta\\:}_{j}{win}_{rt-j}\\)\u003c/span\u003e\u003c/span\u003e + \u003cb\u003eX\u003c/b\u003e\u003csub\u003e\u003cem\u003ert\u003c/em\u003e\u003c/sub\u003e\u003cb\u003eB\u003c/b\u003e\u0026thinsp;+\u0026thinsp;\u003cem\u003eγ\u003c/em\u003e\u003csub\u003e\u003cem\u003er\u003c/em\u003e\u003c/sub\u003e\u0026thinsp;+\u0026thinsp;\u003cem\u003eυ\u003c/em\u003e\u003csub\u003e\u003cem\u003em\u003c/em\u003e\u003c/sub\u003e\u0026thinsp;+\u0026thinsp;\u003cem\u003eδ\u003c/em\u003e\u003csub\u003e\u003cem\u003ey\u003c/em\u003e\u003c/sub\u003e\u0026thinsp;+\u0026thinsp;\u003cem\u003eε\u003c/em\u003e\u003csub\u003e\u003cem\u003ert\u003c/em\u003e\u003c/sub\u003e (1)\u003c/p\u003e \u003cp\u003eThe dependent variable is the natural log of birth rate. Birth rate is defined as the number of births in a region/year-month divided by the number of days in the month, which is further divided by the region/year-month population,\u003ca class=\"FNLink\" href=\"#Fn2\" id=\"#FNLinkFn2\"\u003e3\u003c/a\u003e and then multiplied by 100,000; hence, it is the average daily number of newborns per 100,000 residents. For the variable \u003cem\u003ewin\u003c/em\u003e, mothers have a value of 1 if their home team won the championship 4\u0026ndash;14 months before. For example, because Wyverns won the championship in the 2008 and 2010 seasons, those who gave birth in the Wyverns-based region in January\u0026ndash;November of 2009 and 2011, have a value of 1. The vector \u003cb\u003eX\u003c/b\u003e includes maternal education level and maternal age. In the equation, \u003cem\u003eγ\u003c/em\u003e, \u003cem\u003eυ\u003c/em\u003e, \u003cem\u003eδ\u003c/em\u003e, and \u003cem\u003eε\u003c/em\u003e are the region-, month-, year-fixed effects, and the error term, respectively.\u003ca class=\"FNLink\" href=\"#Fn3\" id=\"#FNLinkFn3\"\u003e4\u003c/a\u003e\u003c/p\u003e \u003cp\u003eThe parameters of interest are betas, indicating the effect of a home team\u0026rsquo;s championship win on the birth rate among women residing in the winning region, presented in percentage form. We anticipate a negative estimate for the birth rate in June (i.e., nine months after a championship win).\u003c/p\u003e\n\u003cp\u003e[3] Population data can be downloaded from the following website of the Korean government:\u0026nbsp;\u003c/p\u003e\n\u003cp\u003ehttps://jumin.mois.go.kr/index.jsp\u003c/p\u003e\n\u003cp\u003e[4] We also estimated the equation controlling for year/month fixed effect, but the results did not change. The results are available upon request.\u003c/p\u003e"},{"header":"4. Data","content":"\u003cp\u003eThe birth registry was collected from the National Statistical Office\u003ca class=\"FNLink\" href=\"#Fn4\" id=\"#FNLinkFn4\"\u003e5\u003c/a\u003e and was based on approximately 2\u0026nbsp;million women who gave live births in January\u0026ndash;November during the 2009\u0026ndash;2013 period. Among them, 120,000 were from Wyverns-based region; 212,000 were from Tigers-based regions; and 202,000 were from Lions-based regions. These winning regions accounted for approximately 26% of the sample.\u003c/p\u003e \u003cp\u003eAs shown in Table\u0026nbsp;\u003cspan refid=\"Tab1\" class=\"InternalRef\"\u003e1\u003c/span\u003e, the birth rate was 2.55, indicating that, on average, 2.55 children per 100,000 residents were born each day. Additionally, 69% of women had a college degree, and the average age was 31.\u003c/p\u003e \u003cp\u003e \u003cdiv class=\"gridtable\"\u003e\u003ctable float=\"Yes\" id=\"Tab1\" border=\"1\"\u003e \u003ccaption language=\"En\"\u003e \u003cdiv class=\"CaptionNumber\"\u003eTable 1\u003c/div\u003e \u003cdiv class=\"CaptionContent\"\u003e \u003cp\u003eDescriptive statistics\u003c/p\u003e \u003c/div\u003e \u003c/caption\u003e \u003ccolgroup cols=\"3\"\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c1\" colnum=\"1\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c2\" colnum=\"2\"\u003e\u003c/div\u003e \u003cdiv align=\"left\" class=\"colspec\" colname=\"c3\" colnum=\"3\"\u003e\u003c/div\u003e \u003cthead\u003e \u003ctr\u003e \u003cth align=\"left\" colname=\"c1\"\u003e\u0026nbsp;\u003c/th\u003e \u003cth align=\"left\" colname=\"c2\"\u003e \u003cp\u003eMean\u003c/p\u003e \u003cp\u003e(1)\u003c/p\u003e \u003c/th\u003e \u003cth align=\"left\" colname=\"c3\"\u003e \u003cp\u003eStandard deviations\u003c/p\u003e \u003cp\u003e(2)\u003c/p\u003e \u003c/th\u003e \u003c/tr\u003e \u003c/thead\u003e \u003ctbody\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eBirth rate\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e2.55\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.29\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eWomen with college degrees (%)\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e69.3\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.07\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eAge\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c2\"\u003e \u003cp\u003e30.9\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colname=\"c3\"\u003e \u003cp\u003e0.56\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colname=\"c1\"\u003e \u003cp\u003eNumber of observations\u003c/p\u003e \u003c/td\u003e \u003ctd align=\"left\" colspan=\"2\" nameend=\"c3\" namest=\"c2\"\u003e \u003cp\u003e770\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003ctr\u003e \u003ctd align=\"left\" colspan=\"3\" nameend=\"c3\" namest=\"c1\"\u003e \u003cp\u003eThe descriptive statistics is from the birth registry and is based on approximately 2\u0026nbsp;million women who gave birth from January to November of 2009\u0026ndash;2013. The birth rate is as outlined in the \u003cspan refid=\"Sec3\" class=\"InternalRef\"\u003eEmpirical Strategy\u003c/span\u003e section. The observations of 770 are derived from 14 regions \u0026times; 5 years \u0026times; 11 months.\u003c/p\u003e \u003c/td\u003e \u003c/tr\u003e \u003c/tbody\u003e \u003c/colgroup\u003e \u003c/table\u003e\u003c/div\u003e \u003c/p\u003e\n\u003cp\u003e[5] The data can be downloaded at https://mdis.kostat.go.kr\u003c/p\u003e"},{"header":"5. Results","content":"\u003cdiv id=\"Sec6\" class=\"Section2\"\u003e\n\u003ch2\u003e5.1. Main analysis\u003c/h2\u003e\n\u003cp\u003eTable\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003e presents the regression results. A home team\u0026rsquo;s championship win did not affect the overall birth rate nine months later; the coefficient is \u0026minus;\u0026thinsp;0.16, and is insignificant. However, when we conducted separate analyses based on educaion level, we found a significant effect among those with a college degree. Specifically, thier birth rate nine months after a home team\u0026rsquo;s championship win decreased by 4.7%. No significant effects ten or more months after the event could imply that the victory had no impact during these months. However, it is also possible that this lack of significance is due to delayed pregnancies coinciding with the continued effects of the win. In other words, delayed pregnancies might increase the birth rate, whereas the continued effects could decrease it, potentially resulting in no significant effect.\u003c/p\u003e\n\u003cdiv class=\"gridtable\"\u003e\n\u003cdiv class=\"colspec\" align=\"left\"\u003e\u0026nbsp;\u003c/div\u003e\n\u003ctable id=\"Tab2\" border=\"1\"\u003e\u003ccaption\u003e\n\u003cdiv class=\"CaptionNumber\"\u003eTable 2\u003c/div\u003e\n\u003cdiv class=\"CaptionContent\"\u003e\n\u003cp\u003eThe effect of a home team\u0026rsquo;s championship win on birth rates 4\u0026ndash;14 months after\u003c/p\u003e\n\u003c/div\u003e\n\u003c/caption\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth colspan=\"11\" align=\"left\"\u003e\n\u003cp\u003eDependent variable\u0026thinsp;=\u0026thinsp;log of birth rate\u003c/p\u003e\n\u003c/th\u003e\n\u003cth colspan=\"1\" align=\"left\"\u003e\u0026nbsp;\u003c/th\u003e\n\u003c/tr\u003e\n\u003c/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd colspan=\"11\" align=\"left\"\u003e\n\u003cp\u003eMonths after a championship win\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd colspan=\"1\" align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e4\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e5\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e6\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e7\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e8\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e9\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e10\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e11\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e12\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e13\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e14\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd colspan=\"1\" align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd rowspan=\"2\" align=\"left\"\u003e\n\u003cp\u003e\u003cstrong\u003eA: All\u003c/strong\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.007\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.011\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.003\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.021\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.009\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u0026minus;0.016\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.017\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.002\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u0026minus;0.000\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.013\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u0026minus;0.005\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e(0.018)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e(0.013)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e(0.008)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e(0.011)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e(0.011)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e(0.012)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e(0.017)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e(0.011)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e(0.013)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e(0.018)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e(0.019)\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd rowspan=\"2\" align=\"left\"\u003e\n\u003cp\u003e\u003cstrong\u003eB: With college degrees\u003c/strong\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u0026minus;0.009\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.012\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u0026minus;0.002\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.014\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.004\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u0026minus;0.047*\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u0026minus;0.002\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u0026minus;0.007\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u0026minus;0.002\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.000\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u0026minus;0.014\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e(0.018)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e(0.014)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e(0.012)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e(0.012)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e(0.014)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e(0.016)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e(0.017)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e(0.015)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e(0.017)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e(0.019)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e(0.023)\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd rowspan=\"2\" align=\"left\"\u003e\n\u003cp\u003e\u003cstrong\u003eC: Without college degrees\u003c/strong\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.019\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u0026minus;0.013\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.004\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.022\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.008\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.020\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.034\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.012\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u0026minus;0.003\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.027\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.000\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e(0.024)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e(0.020)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e(0.015)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e(0.021)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e(0.016)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e(0.025)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e(0.028)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e(0.017)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e(0.021)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e(0.023)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e(0.020)\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd colspan=\"12\" align=\"left\"\u003e\n\u003cp\u003eStandard errors are in parentheses and are clustered at the region/year level. The regression also includes a constant, the proportion of those with college degrees, the average age, region-, year-, and month-fixed effect. The population is used as the weight. The number of observations is 770 in each regression, with adjusted R\u003csup\u003e2\u003c/sup\u003e values of 0.89, 0.90, and 0.97, respectively. *: p\u0026thinsp;\u0026lt;\u0026thinsp;0.05\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003c/tbody\u003e\n\u003c/table\u003e\n\u003c/div\u003e\n\u003cp\u003eFor women without a college degree, the coefficients are 0.020 nine months after the event and 0.034 ten months after. However, none of the coefficients are significant, suggesting that the avoidance of pregnancy during a home team\u0026rsquo;s championship win was not substantial.\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec7\" class=\"Section2\"\u003e\n\u003ch2\u003e5.2. Placebo tests\u003c/h2\u003e\n\u003cp\u003eTable\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003e reveals that birth rates among those with a college degree eight or seven months after a home team\u0026rsquo;s championship win were unaffected. This implies that the significant effect nine months after was not driven by an event that occurred before September of the previous year.\u003c/p\u003e\n\u003cp\u003eAs a placebo test, we assumed that each team won their championship one year earlier. For example, Tigers that won a championship in 2009 were assumed to have won in 2008. This test was conducted using the 2009\u0026ndash;2012 data, and in panel A of Table\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003e, no significant effects were found. We also assumed that each team won championship one year later than the actual year. This test was conducted using the 2010\u0026ndash;2013 data, and panel B of Table\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e3\u003c/span\u003e shows no significant effects. These results imply that reduced birth rate in June (i.e., nine months after a championship win) among those with a college degree (Table\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003e) does not occur every June but specific to the June of the following year after a championship win.\u003c/p\u003e\n\u003cdiv class=\"gridtable\"\u003e\n\u003cdiv class=\"colspec\" align=\"left\"\u003e\u0026nbsp;\u003c/div\u003e\n\u003cdiv class=\"colspec\" align=\"left\"\u003e\u0026nbsp;\u003c/div\u003e\n\u003ctable id=\"Tab3\" border=\"1\"\u003e\u003ccaption\u003e\n\u003cdiv class=\"CaptionNumber\"\u003eTable 3\u003c/div\u003e\n\u003cdiv class=\"CaptionContent\"\u003e\n\u003cp\u003ePlacebo test (those with college degrees only)\u003c/p\u003e\n\u003c/div\u003e\n\u003c/caption\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth colspan=\"11\" align=\"left\"\u003e\n\u003cp\u003eDependent variable\u0026thinsp;=\u0026thinsp;log of birth rate\u003c/p\u003e\n\u003c/th\u003e\n\u003cth colspan=\"1\" align=\"left\"\u003e\u0026nbsp;\u003c/th\u003e\n\u003c/tr\u003e\n\u003c/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd colspan=\"11\" align=\"left\"\u003e\n\u003cp\u003eMonths after a championship win\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd colspan=\"1\" align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e4\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e5\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e6\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e7\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e8\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e9\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e10\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e11\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e12\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e13\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e14\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd colspan=\"1\" align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd rowspan=\"2\" align=\"left\"\u003e\n\u003cp\u003e\u003cstrong\u003eA: Victory one year earlier\u003c/strong\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.020\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.027\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.001\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.018\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.009\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u0026minus;0.016\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u0026minus;0.003\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.016\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u0026minus;0.016\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u0026minus;0.026\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u0026minus;0.017\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e(0.030)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e(0.022)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e(0.016)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e(0.014)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e(0.012)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e(0.016)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e(0.013)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e(0.014)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e(0.013)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e(0.022)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e(0.020)\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd rowspan=\"2\" align=\"left\"\u003e\n\u003cp\u003e\u003cstrong\u003eB: Victory one year later\u003c/strong\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.027\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u0026minus;0.008\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u0026minus;0.015\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.007\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u0026minus;0.005\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u0026minus;0.023\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.010\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u0026minus;0.020\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u0026minus;0.024\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u0026minus;0.008\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u0026minus;0.040\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e(0.032)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e(0.022)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e(0.017)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e(0.015)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e(0.020)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e(0.021)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e(0.019)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e(0.015)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e(0.014)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e(0.023)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e(0.024)\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd colspan=\"12\" align=\"left\"\u003e\n\u003cp\u003ePanel A and B assume that each team won their championship one year earlier or later than the actual year, using the\u003c/p\u003e\n\u003cp\u003e2009\u0026ndash;2012 data and 2010\u0026ndash;2013 data, respectively. Standard errors are in parentheses and are clustered at the\u003c/p\u003e\n\u003cp\u003eregion/year level. Other control variables are the same as in Table\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003e. The population is used as the weight. The number of observations in both panels is 616 (=\u0026thinsp;14 regions \u0026times; 4 years \u0026times; 11 months), with adjusted R\u003csup\u003e2\u003c/sup\u003e values of 0.90 and 0.88, respectively.\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003c/tbody\u003e\n\u003c/table\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e\n\u003cp\u003eTable\u0026nbsp;4: Child care and maternal knowledge based on education level\u003c/p\u003e\n\u003ctable id=\"Tabb\" border=\"1\"\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth align=\"left\"\u003e\u0026nbsp;\u003c/th\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003eWith college degrees\u003c/p\u003e\n\u003cp\u003e(1)\u003c/p\u003e\n\u003c/th\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003eWithout college degrees\u003c/p\u003e\n\u003cp\u003e(2)\u003c/p\u003e\n\u003c/th\u003e\n\u003cth align=\"left\"\u003e\n\u003cp\u003eP-value\u003c/p\u003e\n\u003c/th\u003e\n\u003c/tr\u003e\n\u003c/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e\u003cstrong\u003eA: Child care\u003c/strong\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eI spend time playing with my baby. (%)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e78.2\u003c/p\u003e\n\u003cp\u003e(41.3)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e71.8\u003c/p\u003e\n\u003cp\u003e(45.0)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.00\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eI know what my baby wants and how (s)he feels. (%)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e77.3\u003c/p\u003e\n\u003cp\u003e(41.9)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e71.2\u003c/p\u003e\n\u003cp\u003e(45.3)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.00\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eI show positive and warm interest in my baby. (%)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e91.1\u003c/p\u003e\n\u003cp\u003e(28.4)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e86.2\u003c/p\u003e\n\u003cp\u003e(34.6)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.00\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd colspan=\"4\" align=\"left\"\u003e\n\u003cp\u003e\u003cstrong\u003eB: Maternal knowledge\u003c/strong\u003e\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eBabies in general only understand words which they can speak. (%)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e70.5\u003c/p\u003e\n\u003cp\u003e(45.6)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e53.6\u003c/p\u003e\n\u003cp\u003e(49.9)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.00\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eHow I raise my baby does not affect her/his intelligence. (%)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e88.5\u003c/p\u003e\n\u003cp\u003e(31.9)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e78.7\u003c/p\u003e\n\u003cp\u003e(41.0)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.00\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eBabies\u0026rsquo; characteristics does not change easily six months after birth or afterwards. (%)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e78.5\u003c/p\u003e\n\u003cp\u003e(41.1)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e67.2\u003c/p\u003e\n\u003cp\u003e(47.0)\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e0.00\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003eMaximum number of observations\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e1,264\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\n\u003cp\u003e585\u003c/p\u003e\n\u003c/td\u003e\n\u003ctd align=\"left\"\u003e\u0026nbsp;\u003c/td\u003e\n\u003c/tr\u003e\n\u003ctr\u003e\n\u003ctd colspan=\"4\" align=\"left\"\u003e\n\u003cp\u003eThe information presented in this table is from the Panel Study on Korean Children. Panel A shows the proportion of mothers who chose four or five to five-point likert questions, and panel B displays the proportion of those who knew the correctness of each statement (all three statements are false). Standard deviations are in parentheses.\u003c/p\u003e\n\u003c/td\u003e\n\u003c/tr\u003e\n\u003c/tbody\u003e\n\u003c/table\u003e\n\u003c/div\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec8\" class=\"Section2\"\u003e\n\u003ch2\u003e5.3. Why did we observe significant results only among women with college degrees?\u003c/h2\u003e\n\u003cp\u003eThe differing results in Table\u0026nbsp;\u003cspan class=\"InternalRef\"\u003e2\u003c/span\u003e indicate that the avoidance was more pronounced for women with college degrees. One possible explanation is that they were likely to have more knowledge of child-rearing, making them more aware of the potential negative effects on the birth outcomes for their babies conceived during stressful events. This assertion is in line with the findings of studies, including Streatfield, Singarimbun, and Diamond (\u003cspan class=\"CitationRef\"\u003e1990\u003c/span\u003e) and Schellekens (\u003cspan class=\"CitationRef\"\u003e2021\u003c/span\u003e), who reported that better-educated mothers have greater knowledge of immunizations and sanitations, resulting in improved child survival. Additionally, Currie and Moretti (\u003cspan class=\"CitationRef\"\u003e2003\u003c/span\u003e) found that maternal education improves infant health through increased use of prenatal care.\u003c/p\u003e\n\u003cp\u003eTo verify the above explanation in Korean context, we examined the Panel Study on Korean Children, which is a government-sponsored study of 2,150 singleton babies born during April\u0026ndash;July in 2008.\u003ca id=\"#FNLinkFn5\" class=\"FNLink\" href=\"#Fn5\"\u003e6\u003c/a\u003e An analysis of the Panel supports the aforementioned explanation. For example, as shown in panel A of Table\u0026nbsp;4, 78.2% of those with college degrees chose four or five on a five-point Likert question, \u0026ldquo;I spend time playing with my baby,\u0026rdquo; whereas the number for those without degrees was 71.8% (p-value\u0026thinsp;=\u0026thinsp;0.00). In addition, in panel B, 70.5% of those with college degrees knew the correctness of the statement, \u0026ldquo;Babies in general only understand words which they can speak,\u0026rdquo; whereas the number for those without degrees was 53.4% (p-value\u0026thinsp;=\u0026thinsp;0.00).\u003c/p\u003e\n\u003c/div\u003e\n\u003cdiv id=\"Sec9\" class=\"Section2\"\u003e\n\u003ch2\u003e5.4. Robustness checks\u003c/h2\u003e\n\u003cp\u003eWe conducted two robustness checks. First, to examine whether the findings among those with a college degree were driven by one or two fan base regions, we excluded one fan base region at a time. When we excluded the regions of the Wyverns, Tigers, and Lions from the analysis, the estimate was 2.6%, 5.6%, and 6.4%, respectively, which implies that all three fan base regions were affected by their home team wins.\u003c/p\u003e\n\u003cp\u003eAs another robustness check, we excluded regions with no winning teams and instead included regions with no baseball teams (Nos. 10 and 11 in Figure \u003cspan class=\"InternalRef\"\u003eA1\u003c/span\u003e) to examine whether the betas in Eq.\u0026nbsp;(1) indicate the effect of not winning (or losing) on the birth rate. We found that the corresponding estimate is 3.9%, which is not significantly different from the estimate obtained in the original analysis.\u003c/p\u003e\n\u003c/div\u003e\n\u003cp\u003e[6] The study collects various information on mothers as well as on the babies, and hence, it is possible to examine maternal behavior and knowledge regarding pregnancy and child-rearing, based on education. The data can be downloaded at https://panel.kicce.re.kr/pskc/index.do\u003c/p\u003e\n\u003cp\u003e\u0026nbsp;\u003c/p\u003e"},{"header":"6. Conclusion","content":"\u003cp\u003eWhen in-utero maternal stress has negative impact on offspring\u0026rsquo;s health, it is likely that women tend to avoid pregnancy during times of stressful events. Although previous studies examined the effect of stressful events that occurred \u003cem\u003eduring\u003c/em\u003e pregnancy on live births, few have explored pregnancy immediately after stressful events. We investigated this topic using data from a South Korean professional baseball league. We found that a home team\u0026rsquo;s championship victory reduced the birth rate nine months later among women with college degrees by 4.7%, whereas those without degrees were unaffected. Highly educated women were more likely to be aware of the adverse effects of stress on infant health and, leading them to avoid pregnancy.\u003c/p\u003e \u003cp\u003eAlthough we attributed the decrease in birth rates to the intentional avoidance of pregnancy, it is also possible that these women attempted to become pregnant, but failed due to stress (a biological factor). Additionally, they might have chosen to abort a baby conceived during the championship period due to concerns about birth outcomes. If highly educated women have better access to health care services, including abortion, this could also explain our findings.\u003c/p\u003e"},{"header":"Declarations","content":"\u003ch2\u003eAuthor Contribution\u003c/h2\u003e\u003cp\u003eYoonmin Kim wrote Sections 1 and 2, and Hyunkuk Cho wrote the remaining parts.\u003c/p\u003e\u003ch2\u003eData Availability\u003c/h2\u003e\u003cp\u003edoi: 10.17632/n4btc6w4yk.1\u003c/p\u003e"},{"header":"References","content":"\u003col\u003e\n\u003cli\u003eAnelli, M., \u0026amp; Balbo, N. (2021). Fertility drain or fertility gain? Emigration and fertility during the Great Recession in Italy.\u0026nbsp;\u003cem\u003eDemography\u003c/em\u003e,\u0026nbsp;\u003cem\u003e58\u003c/em\u003e(2), 631-654.\u003c/li\u003e\n\u003cli\u003eBlack, S. E., Devereux, P. J., \u0026amp; Salvanes, K. G. (2016). Does grief transfer across generations? 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Financial incentives, fertility and early life child outcomes.\u0026nbsp;\u003cem\u003eLabour \u003c/em\u003e\u003cem\u003eEconomics\u003c/em\u003e,\u0026nbsp;\u003cem\u003e64\u003c/em\u003e, 101839.\u003c/li\u003e\n\u003c/ol\u003e"}],"fulltextSource":"","fullText":"","funders":[],"hasAdminPriorityOnWorkflow":false,"hasManuscriptDocX":true,"hasOptedInToPreprint":true,"hasPassedJournalQc":"","hasAnyPriority":false,"hideJournal":false,"highlight":"","institution":"","isAcceptedByJournal":true,"isAuthorSuppliedPdf":false,"isDeskRejected":"","isHiddenFromSearch":false,"isInQc":false,"isInWorkflow":false,"isPdf":false,"isPdfUpToDate":true,"isWithdrawnOrRetracted":false,"journal":{"display":true,"email":"[email protected]","identity":"review-of-economics-of-the-household","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"reho","sideBox":"Learn more about [Review of Economics of the Household](http://link.springer.com/journal/11150)","snPcode":"11150","submissionUrl":"https://submission.nature.com/new-submission/11150/3","title":"Review of Economics of the Household","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false},"keywords":"sports event, stress, fertility, birth rate","lastPublishedDoi":"10.21203/rs.3.rs-4922584/v1","lastPublishedDoiUrl":"https://doi.org/10.21203/rs.3.rs-4922584/v1","license":{"name":"CC BY 4.0","url":"https://creativecommons.org/licenses/by/4.0/"},"manuscriptAbstract":"\u003cp\u003eThe literature shows that in-utero maternal stress significantly decreases newborn babies’ birth weight. If this is the case, it is likely that women tend to avoid pregnancy during times of stressful events. We examined this hypothesis using a baseball home team’s championship victory when people likely gather and make a noise, which could affect emotions and stress levels. Data were taken from South Korea, where baseball is the most popular professional sport. As the championship team region changed yearly, we employed a difference-in-differences estimation method. We found that a home team’s championship win did not change the overall birth rate nine months later. However, the birth rate among women with college degrees decreased by 4.7%, while the birth rate among those without degrees remained unaffected.\u003c/p\u003e\n\u003cp\u003eJEL Classifications: D91; I10: J13; Z20\u003c/p\u003e","manuscriptTitle":"Stress and fertility decisions: Evidence from a home team’s championship victory","msid":"","msnumber":"","nonDraftVersions":[{"code":1,"date":"2024-09-17 11:00:21","doi":"10.21203/rs.3.rs-4922584/v1","editorialEvents":[{"type":"communityComments","content":0},{"type":"decision","content":"Revision requested","date":"2025-05-23T19:03:35+00:00","index":"","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2025-05-14T11:16:06+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"96069362377932281738311912778123716520","date":"2025-01-22T09:12:18+00:00","index":"hide","fulltext":""},{"type":"editorInvitedReview","content":"","date":"2024-11-08T19:26:22+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"23191881366005702834212664518124145127","date":"2024-09-09T13:59:42+00:00","index":"hide","fulltext":""},{"type":"reviewerAgreed","content":"53609114199807085333428700824482428505","date":"2024-09-08T13:04:33+00:00","index":"hide","fulltext":""},{"type":"reviewersInvited","content":"","date":"2024-09-05T20:25:38+00:00","index":"","fulltext":""},{"type":"editorAssigned","content":"","date":"2024-08-19T09:50:34+00:00","index":"","fulltext":""},{"type":"checksComplete","content":"","date":"2024-08-19T09:50:04+00:00","index":"","fulltext":""},{"type":"submitted","content":"Review of Economics of the Household","date":"2024-08-16T05:29:16+00:00","index":"","fulltext":""}],"status":"published","journal":{"display":true,"email":"[email protected]","identity":"review-of-economics-of-the-household","isNatureJournal":false,"hasQc":true,"allowDirectSubmit":false,"externalIdentity":"reho","sideBox":"Learn more about [Review of Economics of the Household](http://link.springer.com/journal/11150)","snPcode":"11150","submissionUrl":"https://submission.nature.com/new-submission/11150/3","title":"Review of Economics of the Household","twitterHandle":"","acdcEnabled":true,"dfaEnabled":true,"editorialSystem":"em","reportingPortfolio":"Springer Hybrid","inReviewEnabled":true,"inReviewRevisionsEnabled":false}}],"origin":"","ownerIdentity":"09d03284-4d60-4655-85f4-17ebd8abdbc9","owner":[],"postedDate":"September 17th, 2024","published":true,"recentEditorialEvents":[],"rejectedJournal":[],"revision":"","amendment":"","status":"published-in-journal","subjectAreas":[],"tags":[],"updatedAt":"2025-11-03T15:59:01+00:00","versionOfRecord":{"articleIdentity":"rs-4922584","link":"https://doi.org/10.1007/s11150-025-09808-y","journal":{"identity":"review-of-economics-of-the-household","isVorOnly":false,"title":"Review of Economics of the Household"},"publishedOn":"2025-10-27 15:56:50","publishedOnDateReadable":"October 27th, 2025"},"versionCreatedAt":"2024-09-17 11:00:21","video":"","vorDoi":"10.1007/s11150-025-09808-y","vorDoiUrl":"https://doi.org/10.1007/s11150-025-09808-y","workflowStages":[]},"version":"v1","identity":"rs-4922584","journalConfig":"researchsquare"},"__N_SSP":true},"page":"/article/[identity]/[[...version]]","query":{"redirect":"/article/rs-4922584","identity":"rs-4922584","version":["v1"]},"buildId":"qtupq5eGEP_6zYnWcrvyt","isFallback":false,"isExperimentalCompile":false,"dynamicIds":[84888],"gssp":true,"scriptLoader":[]}