title: Testosterone measured in infancy predicts subsequent sex-typed behavior in boys and in girls.
abstract: The testes are active during gestation, as well as during early infancy. Testosterone elevation during fetal development has been shown to play a role in human neurobehavioral sexual differentiation. The role of early postnatal gonadal activation in human psychosexual development is largely unknown, however. We measured testosterone in 48 full term infants (22 boys, 26 girls) by monthly urinary sampling from day 7 postnatal to age 6 months, and related the area under the curve (AUC) for testosterone during the first 6 months postnatal to subsequent sex-typed behavior, at the age of 14 months, using the Pre-School Activities Inventory (PSAI), and playroom observation of toy choices. In boys, testosterone AUC correlated significantly with PSAI scores (Spearman's rho = 0.54, p = 0.04). In addition, play with a train and with a baby doll showed the anticipated sex differences, and play with the train correlated significantly and positively with testosterone AUC in girls (Spearman's rho = 0.43, p = 0.05), while play with the doll correlated significantly and negatively with testosterone AUC in boys (Spearman's rho = -0.48, p < 0.03). These results may support a role for testosterone during early infancy in human neurobehavioral sexual differentiation.
authors.affiliation: Department of Pediatrics, School of Medicine, University of Eastern Finland, FI-70211 Kuopio, Finland. Annamarja.lamminmaki@kuh.fi
authors.forename: Annamarja
authors.initials: A
authors.lastname: Lamminmäki
authors.forename: Melissa
authors.initials: M
authors.lastname: Hines
authors.forename: Tanja
authors.initials: T
authors.lastname: Kuiri-Hänninen
authors.forename: Leena
authors.initials: L
authors.lastname: Kilpeläinen
authors.forename: Leo
authors.initials: L
authors.lastname: Dunkel
authors.forename: Ulla
authors.initials: U
authors.lastname: Sankilampi
mesh_terms: D000312:Adrenal Hyperplasia, Congenital / Q000378:metabolism; D000328:Adult; D019540:Area Under Curve; D001519:Behavior / Q000502:physiology*; D001724:Birth Weight / Q000502:physiology; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D008423:Maternal Age; D010988:Play and Playthings; D011247:Pregnancy; D012727:Sex Characteristics; D012733:Sex Differentiation / Q000502:physiology*; D011795:Surveys and Questionnaires; D013739:Testosterone / Q000652:urine*
chemical_list: D013739:Testosterone