In addition, although there is a known diurnal vari-

ation in hormone levels in men, phlebotomy oc-

curred throughout the day and time of blood draw

was not captured in data acquisition. As there would

likely be a random distribution across genital

lengths, such measurement variations would likely

lead to a regression to the null. Nevertheless, an

association was found. In addition, only men re-

ferred to and evaluated in our clinic were eligible for

enrollment. Therefore, it is possible that our patient

population does not represent all men.

Nevertheless, our study represents the ﬁrst anal-

ysis to show an association between perineal length

and androgen levels in men. Coupled with recent

data examining adult AGD and sperm production,

AGD may predict normal genital development in

men and, therefore, could provide a novel metric to

assess testicular function. If AGD at birth predicts

adult AGD, our ﬁndings suggest that serum testos-

terone levels in adulthood depend on factors operat-

ing in the fetal period.

ACKNOWLEDGMENTS

Ross Krasnow and Sandra Alexander assisted in

recruiting patients.

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