In a study, researchers found that women rated less masculine faces as more attractive after they went on the pill.
They also found that men who met their girlfriends or wives when they were on the pill were more likely to have masculine features compared to those couples who met while the woman was off the pill.
Millions of women are on some type of hormonal contraceptive, and researchers are becoming more interested in how this affects the choosing of partners.
Published in journal Psychoneuroendocrinology, the study involved heterosexual women ages 18 to 24. Half of the women were taking oral contraception while the other half wasn't.
They were shown pictures of young male and female faces. Participants could alter the faces to appear more or less masculine, like increasing or decreasing the cheekbone prominence, jaw height and face width.
The women who were not taking the pill found men with more masculine features to be more attractive, while women on the pill found men with more feminine features to be more attractive.
There was no effect on masculinity and the attractiveness of female faces.
Researchers were then curious to see if it also applied to the real world, and so compared 85 couples who reported to have met while the woman was on the pill, and 85 couples who met while the woman was not.
They had a group of volunteers judge the male partners faces for masculine features and found that women off the pill were more likely to have a masculine-looking partner.
Other studies have shown that women prefer men with masculine traits when they are ovulating, suggesting that preference for masculine looks may be traced to genetic benefits for potential offspring.
But researchers admit that they cannot determine if the pill is the reason for women choosing more feminine partners or if another variable was involved.
Evolutionary biologist and ecologist Claus Wedekind said that women may choose less masculine looking men when they are on the pill because they are looking for someone "stable." He also suggests they might have "an idea already what the pill does to them, and that influences the experiment."