MELBOURNE -- Couples who get married on "special" days such as Valentine's Day are more likely to get divorced, an Australian study has found.

The University of Melbourne research found that weddings celebrated on Valentine's Day or "special-number-dates" such as Sept. 9, 1999 (9/9/99) or Feb. 1, 2003 (1/2/03) are up to 36 percent more likely to end in divorce.

The report,"Not Your Lucky Day: Romantically and Numerically Special Wedding Date Divorce Risks," said there was up to five times as many weddings on the special days than ordinary dates.

David Ribar, author of the study, said that of the 1 million weddings studied, 11 percent of Valentine's Day marriages, 10 percent of same-number-date marriages and 8 percent of ordinary date marriages had failed by their fifth anniversary.

However, by the ninth anniversary, 21 percent of Valentine's Day, 19 percent of same-number-date and 16 percent of ordinary date marriages had failed.

"People who got married on special dates were more likely to have been married before and more likely to have children already," Ribar said in a media release on Wednesday.

"We also found that spouses who married on special dates were less alike, in terms of education and ages, than spouses who married on ordinary dates," Jan Kabatek, Ribar's co-author, said.

"We also found that brides who married on Valentine's Day were more likely to be pregnant on their wedding day than those who married on ordinary dates."

Ribar said it is not the date that is responsible for increased marriage breakdowns but rather what the date choice reveals about the couple.

"Couples who marry on ordinary dates may be more strongly influenced by characteristics of their relationships and their compatibility than couple who marry on special dates," Ribar said.