Super Bowl Babies: More Boy Births 9 Months Later?

Ah, Super Bowl Sunday. One of the unofficial national holidays of Americans, and second only to Thanksgiving in the amount of food and drink consumed. The annual championship game of the National Football League in the U.S. is often the most-watched television event of the year.

During any big event — whether man-made or natural — researchers often find surprising trends in birth rates. When you follow the data, all sorts of interesting things can be discovered.

Let’s find out how Super Bowl Sunday influences birth rates in America.

Let’s face it. The Super Bowl has become one of those annual pastimes that Americans often use as an excuse to gather, socialize, party, and for some, watch a sometimes-exciting, but all-too-often boring game of American football. Great teams who had a bad game watch forlornly from their own homes, hoping for another shot at the title game next year.

A part of the party-like atmosphere that surrounds Super Bowl Sunday for many couples also involves sex. For psychological reasons, humans seem to have more sex than usual around a major event, whether it’s man-made like this one, or natural (think after a natural disaster, and everyone is safe).

Grech & Zammit (2018) were interested in the question of how the male to female ratio of births is impacted by Super Bowl Sunday, and whether any significant changes they found were influenced by race or area of the country.

According to the researchers, births by race and region were obtained from the Centers for Disease Control and Prevention (the CDC Wonder online database). Since the Super Bowl occurs at the beginning of February every year, in order to determine any effect on birth rates, monthly time series for the period 2003 (for the year 2002) through to 2015 for males, females, and ratio of the two genders were analyzed. “Data was grouped into four US census regions with the four different races for each region,” they noted.

The researchers ended up analyzing over 53 million births during this time period and found just over 27 million males and nearly 26 million females were born. As you can see, there’s a slight edge in male births to begin with, so the researchers needed to adjust their analyses to account for seasonality and other factors that may otherwise cause a significant finding to be hidden in the data.

Stress Causes Less Males to Be Born, Positive Events Cause More Males to Be Born

The present study found support for the hypothesis that male births tend to increase 9 months after the Super Bowl was played. The effect, however, is very small and appears to be really only significant from a statistical point of view. The way the researchers couched their findings suggest as much too:

It is possible that increased coital rates during this period (perhaps due to a combination of celebration and inebriation) may result in the M/T rises nine months later observed in this study.

It’s possible? They may result? They don’t sound too sure of themselves there.

As the researchers note, previous studies have found that stress causes dips in the male-to-female ratio of births, resulting in fewer males being born after stressful events. The Trivers-Willard hypothesis explains this dip as being caused by stressed women who “spontaneously terminate weaker fetuses when experiencing poor conditions. These losses are usually male since males require more maternal resources in order to reach term.”

After World Wars I and II, a study showed an increase in the male birth rate in the countries who were on the winning side of the wars (Macmahon & Pugh, 1953; Russell, 1936). Other research has confirmed this finding. After the birth of Prince William in 1982, male births in England and Wales were up 9 months later (Grech, 2015). After South Africa won the 2010 FIFA World Cup, male births rose 9 months later in that country too (Masukume & Grech, 2015).

There seems to be something to the idea that during stressful times, less males are born, while during times of elation and celebration, more males are born.

Think about that this Super Bowl Sunday, when you’re rooting for your favorite team. Nine months now, don’t be surprised if there are more baby boys than girls being born in the country. Enjoy the game!

 

References

Grech, V. & Zammit, D. (2018). Influence of the Super Bowl on the United States birth sex ratio. Early Human Development, In press, corrected proof, Available online 19 January 2018

Grech, V. (2015). Historic Royal events and the male to female ratio at birth in the United Kingdom, Eur. J. Obstet. Gynecol. Reprod. Biol. 191, 57–61.

Macmahon, B. & Pugh, T.F. (1953). Influence of birth order and maternal age on the human sex ratio at birth, Br. J. Prev. Soc. Med. 7, 83–86.

Masukume, G. & Grech, V. (2015). The sex ratio at birth in South Africa increased 9 months after the 2010 FIFA world cup, Early Hum. Dev. 91, 807–809.

Russell, W.T. (1936). Statistical study of the sex ratio at birth, J. Hyg. 36, 381–401.

 

Our sincerest thanks to Science Direct for access to this academic article, which is in press.

from World of Psychology https://psychcentral.com/blog/super-bowl-babies-more-boy-births-9-months-later/