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The excitement aroused by the World Cup soccer tournament in Germany in 2006 may have increased that country's birthrate as much as 15 percent nine months later. But the intensely emotional matches have now also been correlated with a spike in the number of cardiac emergencies.

A study published Thursday in the New England Journal of Medicine examined the number of cardiac emergencies in the greater Munich area in the summer of 2006. It compared that number with the numbers in similar periods in 2003 and 2005, and for several weeks before and after the 2006 World Cup.

On days when the German team played, the incidence of cardiac emergencies was 2.66 times higher than during the comparison periods. For men, the incidence was 3.26 times higher; for women, it was 1.82 times higher. People with a history of heart disease were particularly affected.

The study's authors say emotional stress was the main trigger, but they add that sleep deprivation, excessive consumption of junk food and alcohol, and smoking might also be contributing factors. They suggest that spectators with heart problems should take preventive measures, such as consulting their doctors about increased medication dosages during intense sports events.

So should Americans be worried about this weekend's Super Bowl? Study author Gerhard Steinbeck says:

It's reasonable to think that something quite similar might happen.

Though if the Vegas odds-makers have it right, the greater danger on Sunday may turn out to be irate New York Giants fans.