Summary of “Stretched Penile Length and its Associations with Testosterone and Infertility”

***Trost Commentary and Key Take-Home Points***

The current manuscript compares penile length and infertility and suggests an association between the two.  This type of study has been performed on several prior occasions as well, although a much more commonly used measure is the anogenital distance (AGD – distance between the anus and the genitals themselves) rather than penile length.  AGD has been linked to genital development overall and is likely more reliable as a measure compared to penile length (since there are several other confounders which can impact penile length and which were not controlled for in the current study).  In general, multiple other studies have reported that men with no sperm (azoospermia) due to production issues and those with low sperm counts have several potential associated conditions, including lower overall survival and increased risks for several malignancies.  The reason for these increased risks is not known, but it may relate to genetic issues which led to under or inappropriate development of the testicles themselves.  These genetic changes may have other effects in the body, including impacts on hormones or other critical components.   


Male infertility is a common issue for men. Some key factors that are associated with male infertility include genetics, trauma, cancer, smoking, alcohol and drugs, obesity, stress, and diet. Some studies have sought to analyze the effect of certain exposures during fetal development to future fertility in males. For instance, anogenital distance (AGD) is linked with male fertility and is caused by endocrine disruptions during the masculinization programming window (MPW), leading to lower androgen exposure which can cause a variety of defects including hypospadias, cryptorchidism low sperm production, and size of genitalia.  

Based on the above associations, this manuscript sought to identify any correlation between stretched penile length and male fertility.  


This study retrospectively analyzed data from many males at a particular men’s health clinic for a 3-year period. Men ages 18-59 were included, unless they had a history of Peyronie’s disease, prior penile surgery, prostatectomy, or receiving testosterone replacement therapy. Stretched penile length was measured in all men in addition to testosterone levels, when available. Men were categorized as either infertile or other (if they presented for infertility specifically or another issue).  


Of the 664 men included (161 infertile and 503 other), 360 of them had testosterone data which revealed a non-significant difference between the 2 groups. The infertile group had a mean stretched penile length of 12.4 cm while men in the other group had 13.4 cm and there was a small correlation between testosterone level and stretched penile length.  


This data suggests an association between a shorter stretched penile length and male infertility and suggests that stretched penile length is affected by AGD and MPW disruptions. Men in the infertility group were younger than, but had a similar BMI to the other group. Androgen exposure, both prenatally and postnatally, has been found to be affect penile growth.  

While there was no difference in testosterone level between the 2 groups, there was a small association between testosterone levels and stretched penile length. The data also suggests that there might be a link between developmental testosterone levels and adult testosterone levels.  

Despite these findings, we cannot conclude that all men with shorter stretched penile length are infertile and not all infertile men will have shorter stretched penile lengths. Even the shorter lengths found in the infertile group are still within the normal adult length range, with an average difference only 1 cm.  


This data suggests an association between stretched penile length and male infertility, in a similar way as AGD. Further studies should continue exploring the possible connections between stretched penile length and AGD and their associations with male infertility.  


Slade AD, Christiansen AR, Keihani S, Brant WO, Hotaling JM. Stretched penile length and its associations with testosterone and infertility. Transl Androl Urol 2021;10(1):49-55. doi: 10.21037/tau-20-788

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