More sex during SA’s World Cup meant more boys nine months on

Nine months after South Africa hosted the 2010 football World Cup a disproportionately higher number of male babies were born compared with the previous eight years. There are two reasons for this: people were having more sex and they were happy.

In our study, published in the journal Early Human Development, we found that nine months after the World Cup, the sex ratio at birth increased. The ratio is defined as the proportion of male babies in the total population of babies born.

The sex ratio at birth can be used to assess the stress a population is under.

When there is stress due to natural events such as earthquakes, floods or man-made events such as terrorist attacks, fewer male babies on average are born, showing a decreased sex ratio at birth. When there are no events adding stress to people, more male babies than female babies are born alive. This means the sex ratio is increased.

Why more boys were born

The percentage of boys born between February and March from 2003 to 2014. supplied

Between February and March 2011 – nine months after the World Cup – the proportion of boys born compared to girls was 50.6%. This is the highest proportion recorded for that time of year since 2003. In previous years, the average proportion for that time of year was about 50.3%. Although this is only a 0.3% difference, which might appear small, it translates to an extra 1 100 male births.

From our statistical analysis, we are 98% certain that this increased birth rate nine months after the tournament was not a coincidence. There are a combination of two factors in the context of our study that result in more male than female children being born. This includes sperm motility, or the ability of sperm to move forward, and how frequently people have sex.

When people have sex more often, on average more boys are born. This relates to the fertile period of a woman’s menstrual cycle. If conception takes place at the beginning or the end of the fertile period, the child is more likely to be a boy. If it takes place in the middle of the fertile period, the child is more likely to be a girl.

In terms of sperm motility, the consequences of negative natural events is that sperm motility is low. This translates into fewer boys being born.

Following the Kobe earthquake in Japan in 1995, sperm motility reduced in men who experienced the severe consequences of the earthquake. Nine months after the devastating earthquake, relatively fewer boys were born than was usual for that time of the year.

Similarly, research shows the death of Princess Diana of Wales in 1997 was followed by a significant fall in the sex ratio at birth in Britain. The research suggests her death was a stressful event for the population.

Had the World Cup caused severe stress, sperm motility would have declined in men and there would have been a subsequent decline in the proportion of boys born. This suggests that sperm motility was unimpaired at population level by the World Cup.

Other studies shows that South Africans were less stressed during the World Cup period.

One conducted in Cape Town during the tournament showed that emergency admissions of those 18 years and younger (the paediatric population) was 37% less than usual relative to periods before and after the event.

Another study showed that up to eight months after the tournament South Africans said they felt good about themselves and their communities. This could be attributed to the country hosting the tournament.

Watching sport does things to the body
There is ample evidence that watching major sporting events can have a biological effect on the population. People have increased emotions when they watch sport.

Research shows that during the 2003 Rugby World Cup semi-final when New Zealand lost to Australia, there was an increase in New Zealand women being admitted to hospital for heart failure and there was an increase in cases of abnormal heart rhythms and heart rates among men in the immediate aftermath of the game. There was a 50% relative increase in admissions for heart failure and a 2.6-fold increase in admissions for abnormal heart rhythms and rates compared to periods when there was no rugby match.

Separate research shows that during the 2006 football World Cup in Germany, when the German national team took to the field, heart attacks and other heart disorders of sudden onset became more common due to emotional stress. Cardiac emergencies nearly tripled in Germany on the days their national team was playing.

And analysing the football World Cups between 1998 and 2010 shows that heart attacks increased in Brazil when the Brazilian national team played in the tournament.

Similarly, in 2010 when the men’s Winter Olympic games ice hockey final between Canada and the US was broadcast, emergency department visits in Ontario – the most populous Canadian province – increased significantly for those classified as experiencing a severe cardiac condition. The games were arguably the most watched television event in Canada’s history.

In 2000, global anti-apartheid stalwart and former South African president Nelson Mandela said:

Sport has the power to change the world. It has the power to inspire, it has the power to unite people in a way that little else does. It speaks to youth in a language they understand. Sport can create hope, where once there was only despair. It is more powerful than governments in breaking down racial barriers. It laughs in the face of all types of discrimination.

These words are clearly supported by biological phenomena.

Gwinyai Masukume is a medical doctor, epidemiologist and biostatistician at the School of Public Health, Faculty of Health Sciences, University of the Witwatersrand and Victor Grech is the Co-Chair of the Humanities, and Medicine and Sciences Programme at the University of Malta.

The Conversation

These are unprecedented times, and the role of media to tell and record the story of South Africa as it develops is more important than ever. But it comes at a cost. Advertisers are cancelling campaigns, and our live events have come to an abrupt halt. Our income has been slashed.

The Mail & Guardian is a proud news publisher with roots stretching back 35 years. We’ve survived thanks to the support of our readers, we will need you to help us get through this.

To help us ensure another 35 future years of fiercely independent journalism, please subscribe.


Where is the deputy president?

David Mabuza is hard at work — it’s just not taking place in the public eye. The rumblings and discussion in the ANC are about factions in the ruling party, succession and ousting him

Zuma turns on judiciary as trial nears

Former president says pre-trial correspondence is part of another plot

High court declares Dudu Myeni delinquent

Disgraced former SAA chairperson Dudu Myeni has been declared a delinquent director by the...

SANDF inquiry clears soldiers of the death of Collins Khosa

The board of inquiry also found that it was Khosa and his brother-in-law Thabiso Muvhango who caused the altercation with the defence force members

Press Releases

Undeterred by Covid-19 pandemic, China and Africa hold hands, building a community of a shared future for mankind

It is clear that building a community with a shared future for all mankind has become a more pressing task than ever before

Wills, Estate Administration and Succession Planning Webinar

Capital Legacy has had no slowdown in lockdown regarding turnaround with clients, in storing or retrieving wills and in answering their questions

Call for Expression of Interest: Training supply and needs assessment to support the energy transition in South Africa

GIZ invites eligible and professional companies with local presence in South Africa to participate in this tender to support the energy transition

Obituary: Mohammed Tikly

His legacy will live on in the vision he shared for a brighter more socially just future, in which racism and discrimination are things of the past

Openview, now powered by two million homes

The future of free-to-air satellite TV is celebrating having two million viewers by giving away two homes worth R2-million

Road to recovery for the tourism sector: The South African perspective

The best-case scenario is that South Africa's tourism sector’s recovery will only begin in earnest towards the end of this year

What Africa can learn from Cuba in combating the Covid-19 pandemic

Africa should abandon the neoliberal path to be able to deal with Covid-19 and other health system challenges likely to emerge in future

Coexisting with Covid-19: Saving lives and the economy in India

A staggered exit from the lockdown accompanied by stepped-up testing to cover every district is necessary for India right now

The best local and international journalism

handpicked and in your inbox every weekday