On the Science of Changing Sex

Lack of In Utero & Perinatal Testosterone Exposure Leads to Childhood Gender Atypicality in Males

Posted in Brain Sex by Kay Brown on June 5, 2022

In a sad “experiment of nature” in which phenotypically normal appearing males are unable to produce gonadotropin, essentially naturally duplicating the effect of puberty blockers, but experiencing this lack since the beginning of the second trimester in the womb. Most importantly, these males do not experience the so called, “mini-puberty” that occurs perinatally, the time just before birth and the first three months after birth.

Given that we have already seen data from a proxy measure of the level of testosterone production and exposure during this developmentally critical period correlates with later childhood gender typicality / atypicality, (Pasterski 2015) we would predict that these individual would also report having being more gender atypical than control men. That is exactly what we see in the recently published study by Shirazi, et al. The is was especially true of those who had cryptochordia (undescended testicle) at birth, indicating even lower T production in utero. Thus, indicating that T exposure before the birth is also important for brain masculinization.

Demographic Statistics Variable Control (n = 463) IGD-clinical (n = 30) IGD-Web (n = 35)
Mean childhood gender atypicality –0.04 (0.33) 0.24 (0.44) 0.34 (0.59)

Mean sexual orientation (Kinsey 0-6) 0.25 (0.94) 0.31 (0.71) 0.94 (1.48)

Interestingly, the effect sizes were not as large as one might expect. To me, this suggests that fetal gonadotropin levels alone may not truly indicate just how much T is being produced given that the fetal adrenal glands are unaffected. Alternatively, it may be that their are Y chromosome canalization effects that we haven’t discovered and accounted for.

It is odd that given that the earlier Pasterski study concerns the same exact subject, and comes to the same conclusion, it wasn’t referenced by Shirazi.

Further Reading:

Essay on Effect of Mini-Puberty on Childhood Gendered Behavior in Boys

References:

Shirazi, et al., “Low Perinatal Androgens Predict Recalled Childhood Gender Non-Conformity in Men”, Psychological Science (2022) https://doi.org/10.1177%2F09567976211036075

Pasterski, V., et al., “Postnatal penile growth concurrent with mini-puberty predicts later sex-typed play behavior: Evidence for neurobehavioral effects of the postnatal androgen surge in typically developing boys”, Hormones and Behavior (2015)
http://www.sciencedirect.com/science/article/pii/S0018506X15000033#f0005

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