Celebrating your wedding during Valentine’s Day is clearly romantic but scientists advice against it. According to economists from the University of Melbourne, weddings on Valentine’s Day or other special-number dates like 9/9/99 or 1/2/03 are 18 to 36 percent more likely to end in divorce than the weddings celebrated on ordinary dates.

Up to five times as many weddings are celebrated on such dates, The Melbourne Institute says. Although other researchers have studied other factors that increase the chances of a marriage ending in divorce, this is the first time that the wedding date has been considered.

The study also finds that couples who celebrated on such dates end up separating by their fifth anniversaries. Specifically, 11 percent of marriages fail when the wedding is on Valentine’s Day and 10 percent when the wedding is on same-number-date. Meanwhile, only eight percent of ordinary-date marriages fail.

Moreover, 21 percent of Valentine’s Day marriages, 19 percent of same-number-date marriages and 16 percent of ordinary-date marriages fail by their ninth anniversaries.

The researchers assert that the date itself does not cause the risk of separation. Instead, the date reveals what kind of people a couple is.

Unlike couples who marry on special dates, couples who marry on ordinary dates are more strongly influenced by their compatibility and the characteristics of their relationship.

Couples who got married on special dates were more likely than couples who married on ordinary dates to have been married before and have children already.

“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,” says Jan Kabátek, a member of the ARC Centre of Excellence for Children and Families over the Life Course. “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.”