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For some women, orgasming during sex is akin to spotting a rainbow-colored unicorn: It's never gonna happen. But like a cruel-cosmic joke, other women have no problem climaxing mere minutes after penetration. What gives, universe?


According to new research published in the journal Clinical Anatomy, some women may be anatomically predisposed to orgasming during penetrative sex. Basically, these women's vaginas are built to work like orgasm machines—while other women's vaginas are not.

For the study, researchers from Indiana University School of Medicine and the Mayo Clinic conducted a meta-analysis on sexual dysfunction studies to better understand why orgasming is difficult for some folks but not for others. To do this, they looked at relevant research papers published over the past several decades on topics ranging from the clitoris to the G-spot, from penile erection to physiological sexual dysfunction. They also looked at research regarding pelvic anatomy variations, "to address how these differences could explain differences in sexual experience, specifically orgasmic success."


So what did they find?

For men, they found that the road to orgasms during sex is pretty straightforward, since the penis and the penis alone is used to achieve orgasm. (And penises are not very complicated.) But a female orgasm involves a network of different anatomical structures—the uterus, vagina, clitoris, and hypothetical Grafenberg, or G-spot—so the path to orgasms during sex can be complex and different for every woman, based on her anatomy.

Most of us already know that the clitoris is key to climaxing—but, as the authors explain, not all clitorises are designed for easy climax during penetration. The key to an orgasm-prone clitoris is location, location, location. Specifically, the distance between the clitoris and the opening of a woman's urethra.

"It is suggested that 2.5 cm from clitoris to urethral meatus is the demarcation in predicting whether or not a woman is likely to have successful orgasms," write the authors in the study. (For reference, this distance can vary in women from approximately 1.6 cm to 4.5 cm)


If these two structures are further than 2.5 cm apart, research suggests it's much more difficult for women to orgasm from penetrative sex. For example, studies have shown that women who suffer from "anorgasmia"—a persistent inability to achieve orgasm—also had increased distances between the clitoris and vaginal opening.

But all hope is not lost. According to the authors, most women whose anatomy doesn't predispose them to penetrative-sex orgasms can still orgasm—they just have to ditch the penis. "Of note, this difference in orgasm was not seen in masturbation, which is congruent with the hypothesis that the distance is only important when the penis is involved," the authors write.


Another key to understanding the female orgasm involves understanding the elusive G-spot, an area inside a woman's vagina that, if stimulated, will surely make her climax every time. Of course, this magical orgasm button is hotly debated, with some studies suggesting it may not exist at all (gasp!). But the researchers of the Clinical Anatomy study didn't see it this way. After analyzing the data, they came up with another theory: The G-spot may manifest differently in different women, which is why it's so damn hard to find.

"It is clear that this 'one size fits all' explanation of female pelvic anatomy is disputed," the authors write. "Perhaps every woman has her own constellation of pudendal nerve branching that creates her own, personal G-spot location."


In other words, the authors propose that the G-spot could just be a nerve-rich area inside a woman's vagina that becomes extra sensitive during sex—and thus, the exact location may vary from woman to woman.

After accounting for the anatomy of the clitoris and the G-spot, the authors found that a couple of additional practical matters contribute to orgasm, too. Specifically: Penile entry angle and obesity.


Penile entry really refers to sexual position, and as the authors point out, different positions stimulate a woman's sexual organs in different ways.

"In posterior entry coitus, studies show that the posterior wall of the vagina is preferentially stimulated, and the anterior wall is more stimulated in the anterior entry," write the authors.


In layman's terms, this means that doing it "doggy style" versus doing it "missionary" will change which parts of the sex organs are stimulated. Which is why some women find they can only orgasm on top, or only in missionary, or only from behind—it could be that, for them, those entries stimulate the right combination of parts.

A woman's weight might also affect her ability to orgasm, too, but not for the reason you might think. As the authors point out, "In a recent study exploring orgasm and waist circumference, larger waist circumference was associated with lesser frequency of vaginal orgasm, but no difference in self-stimulating orgasm."


Catch that? The reason waist size makes a difference might have less to do with anatomy and more to do with psychology. If a woman feels uncomfortable in her body, or unsexy, she may not be able to climax in the presence of her partner. Alone, however, is a different story.

"It seems reasonable to predict that the true difference here is perhaps with partner–partner confidence and less to do with anatomical changes from obesity," write the authors.


So why should we care how our anatomical differences affect our ability to orgasm?

As the authors explain, some women "seem to fall on the beneficial side of the innate anatomy spectrum" and are thus "predisposed" to orgasm. This is very lucky for them. However, other women may have trouble orgasming and blame themselves, believing that something is wrong with them. Rather than have them suffer in self doubt, recognizing anatomical differences can help women understand how to improve their odds.


"For patients, it is important to know that their anatomy could be responsible for sexual inadequacies or sexual success," write the authors. "As such, it is important to study and articulate what these differences could be so that the interventions can be proposed to assist with creating optimal sexual function." Amen.

Taryn Hillin is Fusion's love and sex writer, with a large focus on the science of relationships. She also loves dogs, Bourbon barrel-aged beers and popcorn — not necessarily in that order.