Associations Between the 2nd to 4th Digit Ratio and Autism Spectrum Disorder in Population-Based Samples of Boys and Girls: Findings from the Study to Explore Early Development

Laura A. Schieve, Lin Tian, Nicole Dowling, Lisa Croen, Julie Hoover-Fong, Aimee Alexander, Stuart K. Shapira

Research output: Contribution to journalArticle


The ratio of the index (2nd) finger to ring (4th) finger lengths (2D:4D) is a proxy for fetal testosterone and estradiol. Studies suggesting 2D:4D is inversely associated with autism spectrum disorder (ASD) in males were limited by lack of confounder and subgroup assessments. Studies of females are sparse. We examined associations between ASD and 2D:4D among children in the Study to Explore Early Development; we considered case subgroups and numerous potential demographic and maternal-perinatal health confounders. We observed a modest inverse association between ASD and right-hand 2D:4D in males; subgroup analyses indicated associations were limited to ASD cases with birth defects/genetic syndromes or dysmorphic features. We observed a positive association between ASD and left-hand 2D:4D in females, overall and within most case subgroups.

Original languageEnglish (US)
Pages (from-to)2379-2395
Number of pages17
JournalJournal of Autism and Developmental Disorders
Issue number7
StatePublished - Jul 1 2018



  • Autism spectrum disorder
  • Estradiol
  • Fetal development
  • Testosterone

ASJC Scopus subject areas

  • Developmental and Educational Psychology

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