If you have career aspirations to be a CEO, maybe you should check your birth date.

That's what one study published in an upcoming issue of Economic Letters implies. The study, written by Qianqian Diu from the Shanghai Jiao Tong University in China, Huasheng Gao from Nanyang Technological University in China, and Maurice Levi from the University of British Columbia in Canada, says that fewer children born in June and July go on to become CEOs.

If every month was equally well-represented in the sample obtained from Standard and Poor 500 CEOs, 8.33 percent of CEOs would have been born each month - but that would be assuming that about the same number of infants was born each month. Most infants are born in the months of September, followed by August, June, and July, meaning that, all things being equal, most CEOs should have been born in September, August, June, and July. But, according to the study, which examined the birthdays of 375 S&P 500 CEOs between the years 1992 and 2009, only 6.13 percent of CEOs had been born in June. Babies born in July fared even worse; 5.87 percent of CEOs were born in July. In contrast, babies born in March or April performed much better, with 12.53 percent and 10.67 percent of the sample. In fact, only 12 percent of CEOs were born in June or July, while 17 percent of the population holds the job title.

Researchers believe that the answer to this phenomenon lies in schools' cut-off dates. In the United States, public school districts are generally free to choose their cut-off dates, with most cut-off dates falling between September and January. The researchers say that those born in June and July tended to be among the youngest in their classes, while those born in March or April tended to be among the oldest. "Older children within the same grade tend to do better than the youngest, who are less intellectually developed," Maurice Levi said in a statement. "Early success is often rewarded with leadership roles and enriched learning opportunities, leading to future advantages that are magnified throughout life."

The effect had not been studied for CEOs before, because researchers cannot simply look at birthdays. They have to also look at where CEOs were born, their school districts, and the cut-off dates in their schools in order to support their hypothesis.

This is not the first time that the birthday bias has been theorized to have far-reaching effects. Malcolm Gladwell famously argued in 2008 book Outliers that more professional hockey players in Canada were born in January since, because the cut-off date for hockey registration programs was on January 1, these athletes would have been the oldest.

Still, researchers were surprised that the birthday bias could have effects so far in the future, as most CEOs have been working for many years before achieving such a level in their careers. Maurice Levi says that he believes that the birthday bias has a lifetime effect.

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