Thanks, in part, to online furor surrounding a 2018 study into penis size and fertility, there’s a commonly held misconception that bigger dicks are better at getting people pregnant. Researchers claimed that fertile men had penises around 5.3 inches long when erect, while infertile men’s dicks were 4.9 inches. And despite the scientists concluding that the problem was likely due to underlying issues such as hormonal imbalances or testicular issues — and reassuring healthy people with small dicks that they needn’t worry about their fertility — many still believe that big dicks can get you, er, more pregnant.
The assumed logic here could be that because the normal environment of the vagina is inhospitable to the survival of sperm (due to its low pH levels), the closer the dick cums to the cervix — i.e., the less distance the semen has to travel — the more likely it is to survive. Social psychologist and sex educator Petra Boynton says that, in addition to clickbait headlines, this misconception could also stem from “unscrupulous people online who suggest penis size is related to fertility in order to sell bogus penis enlargement pills and products.”
Unfortunately for people who believe it — but fortunately for people with small dicks — there’s no truth to this theory at all. “Penis size has no bearing on fertility,” says Boynton. “Getting pregnant is down to a number of different factors, but penis size and sexual positions aren’t one of them.”
Boynton says that while the size of the penis doesn’t make any physiological difference, penis size worries can impact on intimacy in that “sex may be avoided or there may be erection difficulties.” She adds, “That most certainly can affect trying to conceive, making what can already be a fraught situation even more tense.”
Clinical psychologist and sex therapist David Ley also firmly debunks this idea. “First, the vagina isn’t all that long, and it generally stretches during sex,” he explains. “The average size penis is plenty long enough to get close to the cervix. Second, there are many confounding factors here, such as testosterone, which can impact both penis size, and testicular size, increasing fertility through sperm count.”
Furthermore, Ley continues, “There’s interesting research suggesting that female bodies and vaginas aren’t simply passive in the fertilization process. Things such as female orgasm affect the pH in the vagina, making it more ‘hospitable’ for sperm.”
Besides, penis-in-vagina sex isn’t even a necessary requirement for sex (see: artificial insemination), says Boynton, so “penis size, shape, sexual positions and orgasm shouldn’t be something people are made to feel anxious about.”
For those who are concerned about fertility, however, Boynton wisely suggests speaking to a doctor — rather than believing everything you read on the internet.