It’s the most unwelcome birthday surprise: death.

People are 14% more likely to die on the day they were born than any other day of the year, a new study found.

And for individuals over 60, that number climbs to 18%.

Researchers at the University of Zurich analyzed data from more than 2.4 million Swiss people who died between 1969 and 2008 and published their findings Monday in the Annals of Epidemiology.

“We concluded that birthdays end lethally more frequently than might be expected,” lead author Dr. Vladeta Ajdacic-Gross told the Independent.

The findings give credence to the “birthday blues” or anniversary theory, which suggests the stress of turning a year older can be lethal.

The bump in birthday fatalities was true for both violent and natural deaths, the study found.

Men were 44% more likely to die in a fatal fall on their birthday than other days of the year, 35% more likely to commit suicide, the study found, and were 29% more likely to perish in an accident.

Excess alcohol consumption during celebrations could be behind the spike in suicides or unplanned slips and falls, researchers speculated.

Natural causes of death were also higher on birthdays. Both women and men were 18.6% more likely to die of complications from heart disease, and for women a 21.5% increase in likelihood of death from stroke, the study found.

Cancer fatalities, which went up 10% on birthdays, were even more likely the day after someone’s birthday, the study found.

Scientists say the higher rates of natural-cause related birthday deaths could be related to the “postponement” theory. According to the theory, people struggling with illness will try to hold on until the big day, at which point the stress associated with a birthday can worsen or trigger disease in someone who is ill or aging, the Independent reported.

“There are two camps,” Professor Richard Wiseman, a University of Hertfordshire psychologist, told The Daily Telegraph. “One is the camp that suggests you eat too much and you’re getting on a bit and that causes you to die,” he said. “The other is a placebo effect. You are knife-edged on death. And you kept yourself going until your birthday. You think ‘that’s it, I’ve had enough, I’m out of here.”

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By Meghan Neal / NEW YORK DAILY NEWS