Contrary to popular belief, a strong jaw and masculine looks may not be what all women want, a new study has revealed.
Women taking the contraceptive pill actually prefer men with more effeminate looks - a trait associated with faithfulness and stability.
Women using the birth control pill were found to rate men with less masculine faces higher in terms of attractiveness compared to non-users.
In couples who first met when the woman was on the pill, the male partners were less likely to have 'manly' faces than those who met when the woman was off the pill.
Millions of women use hormonal forms of contraception and some studies, including this one, indicate the Pill could affect partner preferences.
If supported, these findings could have important implications for how relationships are formed, reported Live Science.
The study, detailed on Saturday in the journal Psychoneuroendocrinology, compared the romantic preferences of straight women ages 18 to 24 who were taking oral contraception against those who were not.
Researchers showed the women composite images of young male and female faces, which could be manipulated to appear more or less masculine (based on features like cheekbone prominence, jaw height and face width).
The women were tested twice - once when none of them were taking the pill and again three months after some began using the pill.
When women were taking the pill, they preferred less masculine male faces (those with more narrow jawbones and more rounded faces, for instance) than before they started taking birth control, the results showed.
Some research suggests that a preference for masculine or feminine traits may be linked to genetic benefits for a couple's offspring, such as strong immune systems.
A few studies have even found that women prefer more masculine traits during the fertile phase of their menstrual cycle.