Behavior, Fertility, & More | Breaking Down the Menstrual Cycle

What Do Short Skirts, Flirting, and Horniness have in Common? Ovulation.

 

Women go through more hormonal changes in a month than men do in their lifetimes. The menstrual cycle is a (reasonably) well-oiled machine involving many different hormones doing many different things, all in the name of perpetuating our species. The levels of hormones change on a daily (even hourly) basis, and those changes can have a significant impact on women’s behaviors.

That may seem like a “duh” statement. After all, we associate key life changes such as puberty, pregnancy, or menopause with behavioral oddities, and pretty much everyone is familiar with the potential terrors of Pre-Menstrual Syndrome (PMS). However, the ordinary menstrual cycle can impact a woman’s behavior in subtle but important ways. Numerous studies have suggested that women’s cyclic changes can influence what they wear, how flirtatious they are, whom they’re attracted to, and even when they cheat.

 

A Menstrual Cycle Primer

To understand how these studies work, it’s important to understand menstrual cycle basics. Women’s cycles vary in length, but the typical example is the 28-day cycle. If you number the cycle days, the onset of the period is Day 1.

 

Days 1-14:

During the menstrual flow, estrogen and progesterone levels are at their lowest, and so is fertility. However, after several days of bleeding, estrogen begins to rise and the uterine lining begins to thicken to prepare to host a fertilized egg. Estrogen levels peak mid-cycle when ovulation (the release of an egg) occurs. Fertility is at its highest here and all those steps take place with the hope of achieving pregnancy.

 

Days 14-28:

Once ovulation has occurred, estrogen begins its decline while progesterone rises in order to nurture any fertilized egg. If the egg isn’t fertilized, both estrogen and progesterone begin to decline and fertility levels decrease. When the levels get low enough, that signals the body to menstruate, which sheds the egg and the uterine lining. Then the cycle begins anew.

 

In other words, a woman’s cycle has both fertile and non-fertile phases and whether or not a woman is in the more fertile phases of her cycle appears to have a significant impact on her behavior.

 

Show Me Some Skin, Baby

During the fertile period in a woman’s cycle, not only is the body preparing for the possibility of pregnancy, she may also dress in a way that could increase the odds of that happening. In a study out of UCLA, researchers took two photographs of young women, one during the fertile mid-cycle phase and the other during the low-fertility phase that occurs two weeks later. Both photos were shown to men and women, who were asked to select the picture in which the woman was trying to look more attractive. In 60% of the cases, they chose the woman in her fertile phase.

What were the differences in these two photos? In those taken during the fertile phase, the women were more likely to dress in a way that’s attractive to men. For example, they showed more skin in their clothing choices, they wore more jewelry, and overall seemed to put more effort into their clothing and appearance.

 

Hello, Mr. Right Now

During ovulation, not only are women more likely to dress in a way that makes them more attractive to men, they’re more likely to don behaviors that interest men. To some extent, the behavior could be explained by the attention that women get from men during their fertile phase, but a study published in Psychological Science found that women’s behavior does change during that time of the cycle.

 

The study examined undergraduate females as they interacted with male actors who were trained to behave like the stereotypical fling (confident and exciting, but unreliable) as well as the stereotypical “safe” guy (warm and stable, but less confident and exciting). The women were told that the “exciting” and “safe” men were identical twins and that they would interact with each.

 

Results showed that the women’s responses to both men were about equal during the low-fertility phase; however, when ovulating, the women displayed more interest in the exciting, short-term fling guy. The women also flirted more overall. This suggests that during the fertile period, women may not only behave in a way that could lead to sex but may do so with men who show no desire for a long-term relationship.

The Forbidden Fruit: Lusting After Other Men

Ever find yourself imagining hot sex with someone other than your partner? Yeah, so have other women. And where you are in your cycle might be at least part of the reason for that.

Pillsworth et al. studied women in long-term relationships and who were not on birth control pills. That latter thing is important because the Pill directly affects women’s hormone levels and prevents ovulation, which can influence behavior. They found that these women had an increased desire for men other than their partners during mid-cycle when ovulation occurs and women are most fertile.

Not only are women more likely to fantasize about having sex with other men during the fertile period of their cycles, they may be more likely to act on these desires during that time. Many people tend to think of men as the infidels of the animal world, but science knows better: women cheat too. And if she does cheat, not only is it more likely to happen during her fertile phase, but she’s more likely to cheat with a man who has traditionally masculine features (e.g. a deep voice, strong jaw).

There are many possible reasons for these findings. Evolutionary psychologists would offer that women are searching for the best possible genes in order to reproduce and create healthy offspring. However, it’s more likely that fertility merely makes women hornier as a way to ensure sex and reproduction. And when you’re really horny, you may crave some big, thick-browed dude with all that masculinity or some random guy you have no long-term interest in. After all, the human species cares more about ensuring its own survival than anything else.

 

 

But, in the end, the observations found in all these studies don’t apply to every woman or every month.

Many, many factors contribute to a woman’s behavior, sex drive, and whom she chooses to sleep with. Yet, when Day 12 comes around and you find yourself choosing that short skirt, you’ll know why.