Besides the cards, cake, candles, and gifts, there might be one more unexpected surprise in store for you on your birthday -- a higher risk of dying.

A new study suggests that men and women are 14 percent more likely to die on their birthday than any other day of the year. This effect was strongest in people aged 60 and older, who were up to 18 percent more likely to die on their birthday.

"We find more deaths than expected solely on birthdays, that is neither in the days before nor after the birthdays," says lead author Dr. Vladeta Ajdacic-Gross, an epidemiologist for the Institute of Social and Preventive Medicine at the University of Zurich.

In this large study, which was published in the Annals of Epidemiology, researchers analyzed data from more than 2.4 million Swiss people who died between 1969 and 2008. They tried to determine if there was any relationship between when people died and the cause compared to their birthdays.

"We were surprised that our findings apply to specific causes of death," says Ajdacic-Gross. Both violent causes, such as suicides and falls, as well as strokes and cardiovascular deaths were tied to birthdays. "In addition, older people are distinctly more vulnerable than younger people," he adds.

Men were more likely to have a violent demise on their birthday, as their chances of suicides spiked by nearly 35 percent and their odds of being accident victims rose by almost 29 percent. Deadly falls in men rose by 44 percent on their birthdays, and, interestingly, the number of falls started to increase about four days before the celebration took place.

When it came to natural causes of deaths, women were at greater risk -- almost 22 percent -- of passing away from a stroke on their birthday. For both ladies and gentleman, there was a nearly 19 percent increase in dying from heart-related reasons.

Scientists also unexpectedly found the risk of dying from cancer jumps by 10.8 percent on birthdays. Cancer deaths also seemed to be higher than usual in the days immediately following a birthday -- a trend not seen for any other cause of death.

But the question you may be asking is: Why? Is birthday partying to blame? Is it a psychological let-down to realize you're one year older -- and not getting any younger?

"We can only speculate on the reasons for the extra deaths on birthdays," points out Ajdacic-Gross. They suspect that birthday-related stress in older people may play a part in the jump in stroke and cardiac deaths.

Other studies have suggested that alcohol may be a reason behind the spike in suicides and perhaps even falls.

The Swiss researchers say their results support the theory of an "anniversary reaction" or "birthday blues," meaning that deaths occurred more frequently on a birthday. They suggest this is a more likely explanation than the "death postponement" hypothesis, or that deaths are less likely to take place on birthdays and people might hang on long enough to reach this yearly milestone -- or to see through certain holidays or special occasions.

Some famous people who have passed away on their birthday include the actress Ingrid Bergman, feminist Betty Friedan, and William Shakespeare.

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