Birth control pills do not alter women's preferences for masculine faces

Each participant viewed pairs of male composite faces that differed in either facial masculinity or facial symmetry. For masculinity, the faces were created by digitally manipulating composite male faces to appear more or less masculine. For symmetry, the same faces were adjusted so that the features on either side of the face were more or less symmetrical. Participants were asked to choose which face in each pair they found more attractive. By comparing these choices at baseline and after three months, the researchers could see whether oral contraceptive use produced any shifts in preference.

The hormonal profiles of the two groups diverged as expected. Women taking oral contraceptives showed lower levels of several reproductive hormones, including luteinizing hormone, follicle-stimulating hormone, testosterone, and estradiol. This confirmed that the treatment was effective. Despite these changes, the study found no statistically significant differences in how much participants preferred masculine or symmetric faces after three months. The estimated effects were small and not distinguishable from zero.

The researchers also explored whether menstrual cycle phase in the placebo group affected facial preferences. Participants returned for the follow-up session at different points in their cycles, allowing the researchers to compare women in the follicular, ovulatory, and luteal phases. Hormone levels were used to verify each woman’s phase.

No significant differences in facial preferences were found between these groups. Similarly, when the team examined correlations between hormone levels and facial preferences, the results showed no consistent associations. Only two out of 132 statistical tests reached conventional significance levels, a number that is roughly what would be expected by chance alone.

The results suggest that previous findings linking menstrual cycle phase or hormonal contraceptive use to shifts in facial preferences may not reflect robust effects. Earlier studies often relied on smaller sample sizes, self-reported menstrual cycle data, and flexible analytic strategies. Those factors tend to increase the risk of false positives and inflated effect sizes. In contrast, this study followed a pre-registered analysis plan and used objective hormonal measurements, which increases confidence in the reliability of its findings.

The researchers also discussed why earlier findings might not replicate. Statistical power is a key factor. Many past studies had small sample sizes, making it easier to detect apparent effects by chance. Some earlier research also lacked pre-registration, allowing researchers to make analytical decisions after seeing the data. This flexibility can unintentionally increase the likelihood of finding spurious results.

Additionally, the assumption that facial masculinity and symmetry reliably signal genetic quality has come under increasing scrutiny. Recent meta-analyses suggest that these traits may not strongly predict reproductive or mating success, which weakens the theoretical basis for expecting hormonal influences on preferences for these specific features.

“We examined the question in every way possible and found nothing,” Apicella told PsyPost. “We compared women taking oral contraceptives to those on a placebo, looked across different points in the menstrual cycle, and examined variation in hormone levels. Preferences for masculinity and symmetry just don’t seem to shift with hormones the way people have claimed.”

“If there’s an effect, it’s likely small. In other words, taking the pill probably doesn’t change the kinds of faces women find attractive in men. These findings also challenge some influential evolutionary hypotheses—like the ‘good genes’ and ‘dual mating strategy’ accounts—which rely on the idea that women’s mate preferences systematically shift with fertility.”

There are, however, limits to what this study can say. The researchers acknowledge that their results apply only to facial masculinity and symmetry. Other traits, such as body shape, scent, or behavioral cues, might still be influenced by hormonal fluctuations. In addition, while the study was well powered to detect moderate effects, it cannot rule out very small effects that fall below its detection threshold.

“We can’t rule out very small effects—our study wasn’t powered to detect those,” Apicella noted. “But, we’re confident that neither oral contraceptives nor hormonal fluctuations produce the kind of bigger shifts in mate preferences that people often talk about. In some ways, it’s not that surprising. Attraction is messy. The heart wants what it wants– just maybe not because of your estradiol levels.”

“Our results only apply to facial masculinity and symmetry. It’s possible that other behaviors or preferences are more sensitive to hormonal shifts. Indeed, there is some evidence that more general mate-related behaviors — things like sexual desire and motivation — may change with a woman’s cycle, but we did not look at that.”

The study, “Oral contraceptives and women’s preferences for facial masculinity and symmetry: Evidence from a double-blind randomized controlled trial,” was authored by Eva Ranehill, Niklas Zethraeus, Coren L. Apicella, Liselott Blomberg, Bo von Schoultz, Angelica Lindén Hirschberg, Magnus Johannesson, and Anna Dreber.

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