Cougars beware — having a boy toy husband increases a woman’s chances of an early death, according to a German study reported Thursday by the Daily Mail.

And the younger her spouse is, the harder it is on a woman's health, researchers found.

However, the trend is reversed when an older man opts for a younger woman. The more youthful his wife, the longer the husband is expected to live.

The finding will come as a blow to the growing numbers of cougars – defined as middle-aged women who shun older men in search of younger guys.

Celebrity cougars include Demi Moore, 47, who is 15 years older than husband Ashton Kutcher, and "Friends" actress Courteney Cox, who is married to film star David Arquette — seven years her junior.

The trend was identified by an analysis of marriage and death records belonging to almost two million Dutch men and women.

A woman who bags a man seven to nine years younger than her is 20 percent more likely to die than someone married to a man her own age. And when a cougar weds someone more than 15 years younger than her, the risk soars to more than 30 percent.

"The greater the age difference, the lower the wife's life expectancy," Sven Drefahl of the Max Planck Institute for Demographic Research in Germany, said. "The best choice for a woman is to marry a man of exactly the same age."

Drefahl believed that having a relationship with a younger man may mean more stress for women because they are "violating social norms and thus suffer from social sanctions," which could result in a more stressful life, he said.

A "sugar daddy" with a wife seven to nine years his junior is seven percent less likely to die early — probably because she's more likely to nurse him in old age. By contrast, a younger man tends to be less inclined to look after his elderly wife. And cougars are more likely to be seen as predatory — making it less likely for them to maintain friends and dependents, another factor researchers suggested could explain their findings.

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