Access Type

Open Access Thesis

Date of Award

January 2015

Degree Type


Degree Name




First Advisor

Sarah Raz


Multiples are thought to be at increased risk for developmental outcome deficits in the preschool years, following preterm birth. However, little research has been conducted to determine whether this group remains at higher risk in the age of artificial reproductive techniques and the modern NICU. The purpose of this study was to investigate whether multiplicity is a risk factor for neuropsychological outcome deficits in a sample of 118 preschoolers (49 multiples, 75 singletons) born prematurely (<34 weeks gestation). As predicted, there were significant relationships between multiplicity and outcome measures, however, the direction of the effects were opposite to our prediction, with multiplies demonstrating superior performance. Additionally, significant multiplicity by sex interactions revealed a female twin advantage over male twin and singleton performance. In this preschool age sample, preterm multiples were not at a disadvantage when compared to singleton counterparts, demonstrating either equivalent or superior neuropsychological performance.