Abstract
The masculinizing effects of prenatal androgens on human neurobehavioral development are well established. Also, the early postnatal surge of androgens in male infants, or mini-puberty, has been well documented and is known to influence physiological development, including penile growth. However, neurobehavioral effects of androgen exposure during mini-puberty are largely unknown. The main aim of the current study was to evaluate possible neurobehavioral consequences of mini-puberty by relating penile growth in the early postnatal period to subsequent behavior. Using multiple linear regression, we demonstrated that penile growth between birth and three months postnatal, concurrent with mini-puberty, significantly predicted increased masculine/decreased feminine behavior assessed using the Pre-school Activities Inventory (PSAI) in 81 healthy boys at 3 to 4years of age. When we controlled for other potential influences on masculine/feminine behavior and/or penile growth, including variance in androgen exposure prenatally and body growth postnally, the predictive value of penile growth in the early postnatal period persisted. More specifically, prenatal androgen exposure, reflected in the measurement of anogenital distance (AGD), and early postnatal androgen exposure, reflected in penile growth from birth to 3months, were significant predictors of increased masculine/decreased feminine behavior, with each accounting for unique variance. Our findings suggest that independent associations of PSAI with AGD at birth and with penile growth during mini-puberty reflect prenatal and early postnatal androgen exposures respectively. Thus, we provide a novel and readily available approach for assessing effects of early androgen exposures, as well as novel evidence that early postnatal aes human neurobehavioral development.
Highlights
The fetal testes begin to produce testosterone (T) and other androgens by week 8 of gestation with T peaking between about weeks 8 to 24 (Reyes et al, 1974; Winter et al, 1976)
Epidemiological studies of healthy men have demonstrated that concurrent measurements of anogenital distance (AGD) predict sperm production, count and quality (Dean and Sharpe, 2013). While these findings suggest that AGD could be a marker of prenatal androgen exposure, which may relate to sexually differentiated behavior in humans, no reports directly linking AGD to human behavior have been published
The larger samples show expected gender-related differences and our subsample of 81 boys was similar to the larger samples of boys in terms of birth weight, birth body length, birth penile length, AGD at birth, and Pre-school Activities Inventory (PSAI) scores
Summary
The fetal testes begin to produce testosterone (T) and other androgens by week 8 of gestation with T peaking between about weeks 8 to 24 (Reyes et al, 1974; Winter et al, 1976). There is a surge of androgens during early postnatal development, often referred to as “minipuberty” (Rajpert-De Meyts et al, 2013), with T peaking at about one to three months postnatal and declining to minimal levels by about 6 months postnatal, where it remains until puberty (Achermann and Hughes, 2011; Kuiri-Hänninen et al, 2011). These early periods of androgen production are necessary for normal development of the urogenital tract, including formation of the external genitalia in early. Studies of individuals with other conditions causing prenatal abnormalities of androgen exposure, and studies relating prenatal androgen exposure to postnatal behavior in typically developing individuals, support the conclusion that prenatal androgen exposure influences human neurobehavioral development (Auyeung et al, 2002; Hines, 2011b; Hines et al, 2002)
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