Objective: This was a prospective study designed to determine the extent to which the degree of exposure to prenatal maternal stress due to a natural disaster explains variance in the intellectual and language performance of offspring at age 5(1/2) while controlling for several potential confounding variables.
Method: Subjects were eighty-nine 5(1/2)-year-old children whose mothers were pregnant during a natural disaster: the January 1998 ice storm crisis in the Canadian province of Québec that resulted in power losses for 3 million people for as long as 40 days. In June 1998, women completed several questionnaires including those about the extent of objective stress (Storm 32) and subjective distress (Impact of Events Scale-Revised) experienced due to the storm. Their children were assessed with the Wechsler Preschool and Primary Scale of Intelligence-Revised (IQ) and Peabody Picture Vocabulary Test-Revised (language) at 5(1/2) years of age, and mothers completed assessments of recent life events and psychological functioning.
Results: Children exposed in utero to high levels of objective stress had lower Full Scale IQs, Verbal IQs, and language abilities compared to children exposed to low or moderate levels of objective prenatal maternal stress; there were no effects of subjective stress or objective stress on Performance IQs. Trend analyses show that for all outcome variables except Block Design, there was a significant curvilinear association between objective stress and functioning.
Conclusions: Prenatal exposure to a moderately severe natural disaster is associated with lower cognitive and language abilities at 5(1/2) years of age.