Sex-specific associations between umbilical cord blood testosterone levels and language delay in early childhood

Background: Preliminary evidence suggests that prenatal testosterone exposure may be associated with language delay. However, no study has examined a large sample of children at multiple time‐points. Methods: Umbilical cord blood samples were obtained at 861 births and analysed for bioavailable testosterone (BioT) concentrations. When participating offspring were 1, 2 and 3 years of age, parents of 767 children (males = 395; females = 372) completed the Infant Monitoring Questionnaire (IMQ), which measures Communication, Gross Motor, Fine Motor, Adaptive and Personal–Social development. Cut‐off scores are available for each scale at each age to identify children with ‘clinically significant’ developmental delays. Chi‐square analyses and generalized estimating equations examined longitudinal associations between sex‐specific quartiles of BioT concentrations and the rate of developmental delay. Results: Significantly more males than females had language delay (Communication scale) at age 1, 2 and 3 years (p‐values ≤. 01). Males were also more likely to be classified as delayed on the Fine‐Motor (p = .04) and Personal–Social (p