Examination of Multiple Birth As a Predictor of Autism Symptoms and Developmental Functioning

Background: Multiple birth is recognized as a significant risk factor for autism spectrum disorder (ASD). However, no one factor, including perinatal risks, has demonstrated etiological causality; this is particularly evident when considering the expansive heterogeneity of the population. Given autism’s multiple etiologies and the fact that ASD remains a behaviorally-defined disorder, understanding similarities and distinctions in behavioral presentation between those who do and do not experience certain risk factors may be beneficial in our continued efforts to subtype ASD.

Objectives: Using a population-level sample, this study aimed to identify discrepancies in demographic and clinical variables among four groups of young children: those who were the product of a multiple birth with and without ASD, and those who were born singly with and without ASD.

Methods: Over 7,000 children, aged 17-37 months old, receiving services through a state-wide early intervention program in Louisiana, USA were included. Information was collected on their family and medical histories as well as their ASD symptomology and developmental functioning. Categorical data were compared across groups using Chi-Square tests; continuous data were examined with univariate and multivariate analyses of variance, using appropriate corrections where applicable.

Results: Significant between-group differences were found in the occurrence of prematurity, parental age at birth, and the presence of several medical conditions, including seizures and cerebral palsy. Discrepancies in autism symptom severity and developmental functioning among the four groups were primarily explained by the presence of an ASD classification; multiple birth status did not contribute meaningfully to the presentation of social and communication impairments and restricted, repetitive behaviors nor to functioning across a number of developmental domains.

Conclusions: While multiple birth was associated with a number of medical factors, it was not predictive of poorer developmental functioning or greater ASD severity during young childhood. Rather, differences found between groups were largely attributable to the presence of ASD. Given the difficulties teasing apart pre-, peri-, and postnatal complications as potential contributors to autism risk and that obstetric optimality was assumed for singletons, ongoing analyses are continuing on the clinical characterization of variably at-risk groups. A composite measure of risk comprising multiple pregnancy and birth complications rather than considering single factors may perform better in delineating diverse trajectories to ASD.