BIRTH RATE MAY INCREASE NINE MONTHS AFTER NATIONAL FOOTBALL SUCCESS.

Editor,

We noted an increase in referrals to prenatal genetic clinics after large sporting events such as the UEFA European Championship (Euros) and World Cups. Few reliable studies are reported, although birth spikes nine months after events are described in South Africa after they hosted the 2010 FIFA World Cup[1], the USA Super Bowl championship[2] and following a last-minute goal by Barcelona in the 2009 UEFA final[3].

We examined live birth rates nine months after the six UEFA Euros and FIFA World Cups, between 2006-2017[4]. The expected due date (E.D.D) of births, conceived during the period, was calculated as 38 weeks following the beginning and end of the tournaments, assuming births at ~40 weeks gestation. The tournaments occurred in June - July, so the E.D.D range corresponds to the following March (Table 1). We compared live births in March, as a proportion of total births for the corresponding year, with the average birth rate in the contiguous February and April, using chi-squared analysis.

TABLE 1

FIFA World Cup and UEFA Euros start and finish dates with corresponding expected due date (E.D.D), 2006-2017.

	Tournament start	Tournament finish	E.D.D start	E.D.D finish
FIFA World Cup	12/06/2014	13/07/2014	05/03/2015	05/04/2015
	11/06/2010	11/07/2010	04/03/2011	03/04/2011
	09/06/2006	09/07/2006	02/03/2007	01/04/2007
UEFA Euros	10/06/2016	10/07/2016	03/03/2017	02/04/2017
	08/06/2012	01/07/2012	01/03/2013	24/03/2013
	07/06/2008	19/07/2008	28/02/2009	11/04/2009

RESULTS

Birth rates for the following March ranged from 1,780 to 2,113 (7.3% to 9.2% as a proportion of total births for each corresponding year). Average birth rates for February and April combined, ranged from 1,930 to 1,873 (7.2% to 8.1%) (Table 2).

TABLE 2

Comparison of proportionate births in March and February/April, corresponding to the E.D.D for conceptions occurring during World Cup and UEFA Euros tournaments (2007-2017).

Year	March birthsa % (n)	Average February/April birthsb % (n)	Difference in births (%) March v. February/April	p. valuec	95% Confidence Intervalsc
2017^	9.2 (2,113)	7.2 (1,658)	2	0.008	0.5136 - 3.5493
2015*	8.1 (1,966)	7.7 (1,873)	0.4	0.593	1.0399 - 1.9231
2013^	7.3 (1,780)	8.1 (1,930)	0.8	0.298	0.7353 - 2.2324
2011*	8.6 (2,181)	7.3 (1,856)	1.3	0.072	0.1136 - 2.7810
2009^	8.4 (2,086)	8.1 (4,023)	0.3	0.685	1.1229 - 1.8014
2007*	7.9 (1935)	7.7 (3,765)	0.2	0.789	1.2340 to 1.7202

a. March births (%) calculated as a proportion of total births for the corresponding year.

b. Average of February and April births, calculated as a proportion of total births for the corresponding year.

c. P.values and 95% Confidence intervals calculated using chi-squared test.

^ Year corresponding to a conception during a UEFA European Championship.

* Year corresponding to a conception during a FIFA World Cup Championship.

We observed no significant difference in the proportion of live birth rates between 2007 – 2015, however, a statistically significant increase in births was noted in March 2017, nine months after the 2016 UEFA Euros Championship, compared with the contiguous February and April (2% (0.516 to 3.549), p 0.008) (Table 2). 2016 was the first occasion when the Northern Ireland (NI) football team qualified to compete in the UEFA Euros tournament and the team achieved relative success, reaching the second stage.

We postulate that the increase in birth rate nine months after NI’s first appearance in the UEFA Euros may be the result of a potent combination of national excitement, enthusiastic fervour, celebration and inebriation.

Although there are few existing studies looking at the relationship between sporting events and birth rates, our findings are consistent with the South African World Cup, the USA super Bowl and Barcelona UEFA reports [1-3]. Mechanisms by which large sporting events influence reproductive behaviour are complex. Increased alcohol consumption, disinhibited behaviour and a sense of well-being as a result of national pride and excitement, may play a role. The association between the March 2017 birth rate in Northern Ireland and the timing of the 2016 UEFA Euros tournament does not prove causation and there may be other factors such as seasonal light and temperature variations and no significant rise in birth rate was noted following the other five football tournaments that we examined.

Future research may look at other sporting events (e.g. Olympics, Rugby World Cup). Any impact on reproductive behaviour may depend on which national team is competing and the degree of their success within the tournament. Following the relative success of England in the 2018 World Cup, we may see a spike in “World Cup babies” in March 2019.

CONFLICT OF INTEREST STATEMENT

The authors have no conflict of interest to declare