Objectives: To examine how prenatal and postnatal sex steroid hormone levels are associated with individual differences in autistic traits in 18-24 month old children.
Methods: Fetal testosterone (fT) and fetal estradiol (fE) levels were measured in amniotic fluid using radioimmunoassay from pregnant women following routine second-trimester amniocentesis in n=129 toddlers. Saliva samples were collected from a subset of these children (n=35) when they reached 3-4 months of age. Salivary samples were assayed (without separation or extraction) for neonatal testosterone (nT) levels using commercially available immunoassay protocols. When the children reached 18-24 months of age, mothers were asked to complete the Quantitative Checklist for Autism in Toddlers (Q-CHAT), a measure which has been shown to be effective in detecting the presence of autistic traits.
Results: fT levels were positively associated with scores on the Q-CHAT. For the smaller subset of children for which nT was measured, nT levels showed no significant sex differences and no relationships with FT levels or with Q-CHAT scores. The same subset retained the relationship between fT levels and Q-CHAT scores, despite the smaller sample size.
Conclusions: These findings are consistent with the hypothesis that prenatal (but not postnatal) androgen exposure (coinciding with a critical phase in sexual differentiation of the brain) is associated with the development of autistic traits in 18-24 month old toddlers. The present results should be followed up in a larger sample to examine whether individuals with clinical diagnoses of autism had elevated levels of fT.