We know there’s a wide variation in how people with vulvas experience orgasm. Some come easily, while others might go their whole lives without one. But why? Some researchers suggest how often you orgasm during P-in-V sex has to do with the location of your clitoris. Specifically, the distance between your clitoris and vagina (C-V distance), or the distance between your clitoris and your urethral meatus, or urethral opening (CUMD).
According to the Los Angeles Times, this idea goes back to the 1920s, when Princess Marie Bonaparte — a psychoanalyst, Napoleon’s great-grandniece, and a close friend of Sigmund Freud — got frustrated with her own lack of orgasm and began gathering data from her patients. She found that women with a clitoris fewer than 2.5 centimetres from their vagina – around the distance of the tip of the thumb to the first knuckle – orgasmed more frequently during penis-in-vagina sex. She called this the "rule of thumb". Eventually, Bonaparte underwent two experimental surgeries in an attempt to bring her clitoris closer to her vagina — which, according to ABC News, didn’t go so well. Bonaparte abandoned her project.
In the 1940, a group of researchers led by Carney Landis undertook a similar study, and discovered that women who orgasmed more frequently during P-in-V sex had a shorter distance between the vagina and urethral opening. "On the physical side, orgasm capacity is related to clitoris-meatus distance," they concluded.
Then, in the 2000s, Kim Wallen and Elisabeth Lloyd reanalysed Bonaparte’s and Landis’ raw data with modern statistical techniques. In their 2011 study, they found that both datasets "demonstrate a strong inverse relationship between CUMD and orgasm during intercourse." They add that people with a shorter CUMD may experience more orgasms because the location of their clitorises mean they have more clitoral stimulation during P-in-V intercourse.
But don't run to find a tape measure just yet. Wallen and Lloyd weren’t able to take C-V or CUMD measurements for women today because, according to the Los Angeles Times, they couldn’t develop a reliable at-home measuring technique, especially one that could account for stretchy skin. So we’re talking about just two datasets here: one from the 1920s, and another from the 1940s.
Wallen even warned people not to take these measurements too seriously. "Personally, I don’t think the inability to experience no-hands, penis-only intercourse with orgasm says anything about a happy sex life," he told the Los Angeles Times in 2008. "Maybe it could allow couples to be a bit more inventive in how they have sex." There are many ways to have sex besides P-in-V, after all.