Science + Technology

Forget Basal Body Temperature -- Check Out Her Clothes; Signs of Ovulation May Be More Obvious Than Supposed, Suggests New UCLA and Wisconsin-Eau Claire Study


Was Chris De Burgh's sexy "Lady in Red," perhaps, ovulating?A new UCLA and University of Wisconsin-Eau Claire study finds evidence thatwomen put more effort into their clothing and grooming during their mostfertile periods.

"Near ovulation, women dress to impress, and the closerwomen come to ovulation, the more attention they appear to pay to theirappearance," said Martie Haselton,the study's lead author and a UCLA associate professor of communication studiesand psychology. "They tend to put on skirts instead of pants, show more skinand generally dress more fashionably."

Conventional wisdom has long held that humans hide all signsof ovulation, even from themselves and their mates. Indeed, numerous scientific studies have beendevoted to identifying what the evolutionary advantage might be to disguisingfertility.

Yet the study, which publishes Oct. 10 in the online versionof the scholarly journal Hormones and Behavior, found that even total strangerscould detect a difference in women's grooming habits when they approachedovulation.

"The thing that's so remarkable about this effect is thatit's so easily observed," said April Bleske-Rechek,the study's co-author and an assistant professor of psychology at University ofWisconsin-Eau Claire. "In our study,the approach of ovulation had a stronger impact on the way women dressed thanthe onset of menstruation, which is notorious for its supposedly deleteriousimpact."

Haselton, Bleske-Rechekand three UCLA students tracked 30 college coeds in committed relationshipsthrough an entire ovulatory cycle. Using urine teststhat are nearly as accurate for determining ovulation as ultrasounds, theyascertained each woman's most fertile period — about 10 to 15 days aftermenstruation — and their least fertile period — roughly the two weeks followingovulation.

The researchers photographed the women twice: once in theirfertile (follicular) phase and another time in their non-fertile (luteal) phase. To ensure that only the women's attire,grooming and accessories were taken into account, researchers maskedparticipants' faces in the photographs with black ovals.

Researchers then arranged the photos in pairs on a kind ofscientific version of the Web site "Hot or Not." Forty-two judges — a little more than half ofthem women — were asked, "In what photo is the person trying to look moreattractive."

In 60 percent of the cases — a frequency well beyond randomchance — the judges picked the high-fertility photos.

"Many things affect the clothing that women decide to put onwhen they leave the house, including whether they have an interview to go to orwhether they're going to the library to study for an exam or what they haveplanned after school," Haselton said. "Just one ofthem is a somewhat subtle event that changes their biochemistry. And yet thischange manifests itself in an observable and pretty dramatic difference in howwomen dress."

In one pairing, the participant wore loose-fitting jeans andclunky boots in her low-fertility photo and a skirt and cardigan in herhigh-fertility photo. In another, the participant appears to be wearing thesame black yoga pants in both photos. She also is wearing the same sort ofshirt in both photos — a tank top. But in the low fertility photo the top is abasic, white model, while the high fertility model is a pretty color, with aslightly lower-cut neck trimmed in lace, and it's accessorized with a fanciernecklace. In another pairing, the participant had donned a fringy scarf for herhigh-fertility photo.

The undergradsdemonstrated little knowledge of the workings of ovulation and certainlyweren't tracking their cycle or attempting on any conscious level to getpregnant.

Yet the women not only seemed to have paid more attention totheir appearance as they approached their most fertile period, but the morefertile the women were, the more likely their pictures were to be selected.

Interestingly, the approach of menstruation did not seem tohave any observable effect on how the women dressed, suggesting that, at leastin this study, the onset of ovulation had a greater impact on a woman'sdressing habits than so-called PMS (pre-menstrual syndrome).

"There's a popular notion that when women approach menstrualonset, they get out their bloated clothes and they pull out their sweats," Haselton explained. "So if what we were measuring was a PMSeffect, you'd expect that if a woman has her photo taken one or two days beforemenstrual onset, then she's going to dress frumpier than someone who had herphoto taken 10 days before menstrual onset. But we didn't find that to be thecase."

The research builds on a new body of research showing subtleand surprising shifts in women's behavior each month as they approach theirmost fertile period, including a propensity to flirt with men other than theirmates and an inclination to stray from their routine in ways that aresuggestive of mate-shopping.

Meanwhile, the findings conflict with conventional wisdomamong social scientists, who have long maintained that humans are rare amongprimates in showing no outward signs of entering fertile phases. Our closest living relative, the Chimpanzee,famously displays swellings of the genital area when fertile.

"Something in women's minds is tracking the ovulationcycle," Haselton said. "At some level, women 'know'when they are most fertile. And we haveseen some evidence that men may at some level 'know' too – although with lesscertainty."

Haselton and Bleske-Rechek,however, stop short of ascribing the changes they have detected to the kinds ofdisplays of fertility that are common in the animal kingdom.

The changes may well be the byproduct of the "stew ofchanges" to which, mounting evidence suggests, women are subject as theyapproach the most fertile point of every cycle. In addition to a desire tocheat on long-term mates who are less than virile, researchers have found someevidence that women's facial features may be more attractive and they may evenfeel sexier as they approach ovulation, which comes midway through every cycle.

"Women may decide, 'Hey, I'm looking good!' And this affectsthe items they pick to wear." Haselton said.

Whatever the woman's motivation, the behavior may explain achange that has recently been quantified in men's behavior around ovulation. Men appear to respond with increase mate-guarding, Haselton has found.

"When women are in their high fertility phase, theirpartners are more attentive and loving toward them," Haseltonsaid. "But we don't know exactly what it is that men are picking up on. Quitepossibly, it could be something about women's behavior, including their styleof dress."



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