Poor Sandra Bullock — she was the toast of Hollywood in 2010 after winning the best actress Oscar for The Blind Side, a woman seen by fans as the perfect girl next door and a sentimental favourite for the prize. Then, within weeks, her husband, Jesse James, became a tabloid headline for his infidelity, and the couple had split acrimoniously.

In breaking up with her partner after winning an Academy Award, Bullock followed in the footsteps of predecessors such as Halle Berry, Joan Crawford and Bette Davis.And she held out a painful example for this year's nominees – which include Annette Bening, Natalie Portman, Nicole Kidman, Jennifer Lawrence and Michelle Williams.

Best actress winners are at considerably higher risk of divorce than non-winners – about 1.68 times more likely to split from a husband or partner.

It's called the best actress Oscar curse, and a group of researchers has shown it's more than just a popular perception.

Sue Moon and Tiziana Casciaro of the University of Toronto and Colleen Stuart of Carnegie Mellon University in Pittsburgh set out to apply some scientific rigour to the field with their paper The Oscar Curse: Status Dynamics and Gender Differences in Marital Survival.

What they found was that best actress winners are at considerably higher risk of divorce than non-winners — about 1.68 times more likely to split from a husband or partner. But winning a best actor award did not seem to have the same effect on men.

When Halle Berry won the best actress award for Monster's Ball in 2002, she divorced from her husband, singer Eric Benet, the following year. Denzel Washington won the best actor nod for Training Day that same year, and he's still married.

"It actually does speak to a quite important issue, which is how success for different members of a population is viewed differently, and it has different effects for them," said Stuart, a post-doctoral fellow at Carnegie Mellon University, in an interview with CBC News.

For the purposes of the study, the best actress winners were compared to best actress nominees, who Stuart says would have similar ages and would probably be working as hard at their careers as the winners.

"What we did is we compared the risk of divorce among best actress winners and nominees who were married or in a common-law relationship, because we thought the population is reasonably similar to one another," she said.

The researchers went back to 1936, the beginning of the modern Academy Awards. Earlier in Oscar history, an actor or actress might be nominated for a body of work, instead of an individual film. The study looked at marriage longevity for 751 best actor and actress nominees in that period.

Stuart said there is statistical evidence that the best actress Oscar curse is more than a popular myth. The median length that the marriage of a best actress Oscar winner lasts after her nomination is 4.3 years; for non-winners, it's 9.5 years. Among best actors, there isn't much difference between winners (11.8 years) and non-winners (12.6 years).

Even in much-married and -divorced Hollywood, those are short time spans. For every long-lasting marriage, like that of Meryl Streep or Susan Hayward, there is a Faye Dunaway, divorced three years after her win for Network, or a Liza Minelli, married and divorced four times, the first time two years after her best actress win for Cabaret.

'It could be ... due to the husband's discomfort with his wife's fame and success. It could also be that after this award, the wife may grow dissatisfied with her current marriage.'

— Colleen Stuart, post-doctoral fellow at Carnegie Mellon University

"It could be the difference is due to the husband's discomfort with his wife's fame and success," Stuart says. "It could also be that after this award, the wife may grow dissatisfied with her current marriage. Either because she's outgrown the relationship or because she is now so confident and has the opportunity to move away from a bad marriage."

There is related research to back up this dynamic. Social scientists have found in studies that men stay away from partners whose intelligence and ambition exceeds their own. A wife's high income has been linked to divorce in couples with a range of incomes, but especially where the wife's earning power outstrips the man's.

"Research has shown that, in the general population, gender differences have historically given roles with greater power and status to men and roles with lesser status and power to women," said Casciaro, an assistant professor of organizational behaviour at U of T's Rotman School. "Studies have demonstrated that breaching this social norm within a marriage — for example, when a wife earns more than her husband — can strain the relationship."

Stuart acknowledges there is no way of knowing what is going on inside a marriage – either a good one or a bad one. The research team looked over biographies of actresses from earlier eras and newspaper articles from the time, but did not find reliable information about other common factors that could lead to marriage breakdown.

Best actress nominees do tend to lead colourful lives. Joan Crawford was married four times and got her third divorce the year after she won best actress for Mildred Pierce in 1946. She'd been nominated twice before, for Sudden Fear and Possessed. Bette Davis won twice, in 1935 for Dangerous and 1938 for Jezebel. She was notorious for her many affairs and her husband, Ham Nelson, divorced her in 1938, citing infidelity (namely, an affair with Howard Hughes).

Looking at this year's best actress nominees, Jennifer Lawrence and Michelle Williams appear to be single, Nicole Kidman has been married to country singer Keith Urban since 2006 and a glowingly pregnant Natalie Portman is engaged to ballet dancer Benjamin Millepied.

Annette Bening has been married to Warren Beatty since 1991. Beatty has been romantically involved with two previous best actress winners — Diane Keaton and Julie Christie. What are the odds?