Husbands who earn less than their wives are more likely to under-perform between the sheets, a new study has found.

They are also more likely to need performance enhancing drugs such as Viagra to help overcome their feelings of loss of pride, anger and frustration in the bedroom.

Research by Danish and US scientists revealed that Viagra and other drugs for impotence were particularly popular in households where the woman was the main breadwinner, The Daily Mail reported.

The researchers studied the salaries and prescription data of more than 20,000 married couples.

“Even small differences in relative income are associated with large changes in erectile dysfunction medication usage when they shift the marriage from a male to a female breadwinner,” the research, published in thePersonality and Social Psychology Bulletin, said.

This effect was also true even when the wife’s salary was only slightly higher than the husband’s. A wage difference of $15,000 (S$18,523) in the wife’s favour doubled the odds of Viagra use.

However, the research found these results were limited to couples where the wife’s wages had overtaken her husband’s over time – not in cases where the woman started as the higher earner.

In the US, the proportion of wives who earn more than their husbands has more than quadrupled in the last 20 years.