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Access Type

WSU Access

Date of Award

January 2019

Degree Type

Dissertation

Degree Name

Ph.D.

Department

Psychology

First Advisor

Sarah Raz

Abstract

Increased attention to medical risk factors that precede or accompany preterm birth is necessary in order to better understand functional deficits in this vulnerable population. Children who are born preterm are subject to increased risk of neurodevelopmental deficits in the preschool years and beyond. As such, the current study aimed to gain a better understanding of the influence of two disparate biological risk factors, one antenatal and the other perinatal, on neuropsychological development. More specifically, the influence of twin gestation and low arterial pH (reflecting hypoxic risk) on neuropsychological outcomes was examined in a sample of preterm-born (before 34-weeks gestation) preschoolers (age 3-4). Additionally, differences within-twin pairs with discordant risk were explored.

Contrary to my prediction, there were no differences between twin and singleton performance on cognitive, language, or motor outcomes. However, significant within-pair differences were found when exploring differences between higher and lower risk co-twins with discordant (>1/3 SD) birth weight (n = 28 pairs). The higher risk twins (lower birthweight) demonstrated poorer performance in the cognitive and motor domains relative to their lower risk co-twins. Consistent with my predictions, lower pH values (higher hypoxic risk) in a combined group of twins and singletons (n = 151) were associated with poorer cognitive, language, and gross motor performance in preterm-born preschoolers. Taken together, while this study did not reveal a unique effect of multiple birth on outcome, I was able to show that relatively small differences in birth weight SD between co-twins resulted in outcome effects. The findings from the second major component of this study suggest that even subtle changes in pH, an index of fetal physiology, in preterm born children may be linked to corresponding changes in developmental outcomes in the cognitive, motor, and language domains at preschool age.

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