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The purpose of this review is to summarize the current state of knowledge on how nongenetic factors occurring before, during, or soon after birth are related to schizophrenia. Schizophrenia is a complex psychiatric illness with a varied clinical presentation that has both environmental and genetic origins and that may result from insults to the nervous system that occur throughout development. In line with this, several endogenous (internal) and exogenous (external) nongenetic factors of pregnancy and birth have been related to an increased risk for schizophrenia in later life. These factors include maternal diabetes, low birth weight, older paternal age, winter birth, and prenatal maternal stress, among others. Although each of these nongenetic factors alone slightly increases the risk for schizophrenia, risk increases when these factors combine with each other and with other risk factors. The mechanisms that link each specific risk factor with the occurrence of schizophrenia remain largely unknown. In order to build better models of the illness, researchers will have to address the question of how environmental and genetic risk factors work together in increasing risk and explore to what extent certain underlying risk factors may explain different aspects of the disease. [ABSTRACT FROM AUTHOR]

Objective: This report presents a French translation and validation of the Impact of Event Scale-Revised (IES-R) in a population of women exposed to a natural disaster during or preceding pregnancy.Method: A total of 223 francophone women who were either pregnant at the time of the 1998 ice storm or who became pregnant shortly thereafter completed the IES-R and other questionnaires 6 months after the disaster.Results: The French IES-R has good internal consistency, with alpha coefficients ranging from 0.81 to 0.93 for its 3 subscales and total score. The test-retest reliability of the scale, although examined with another sample, proved to be satisfactory, with correlation coefficients ranging from 0.71 to 0.76 for its 3 subscales and total score. Its convergent validity with perceived life threat and general psychiatric symptoms was judged to be marginally acceptable. Finally, a principal components analysis was conducted and a 3-factor solution, which explained 56% of the variance, was retained: a hyperarousal factor (7 items), an avoidance factor (6 items), and an intrusion factor (6 items).Conclusions: The French version of the IES-R has satisfactory internal validity and test-retest reliability. Further, the factor structure of the translation was similar to the proposed theoretical structure of the IES-R. [ABSTRACT FROM AUTHOR]