Psychotic illness after prenatal exposure to the 1953 Dutch Flood Disaster

We tested the hypothesis that maternal stress during pregnancy increases th e risk of non-affective psychosis for the child. The concept of non-affecti ve psychosis includes the ICD categories schizophrenic disorder, paranoid s tate and other non-organic psychosis. Data from the Dutch Psychiatric Regis try were examined for an effect of the Flood Disaster of 1 February 1953. O n this day, a gale caused a flood in the South-west of The Netherlands and 1835 people perished. Our study concerned the 19 villages where mortality e xceeded 0.25%. The risk of non-affective psychosis for the cohort born in t he period February-October 1953 was compared to the risks for the cohorts b orn in the corresponding periods of the previous and subsequent 2 years. Th e relative risk of non-affective psychosis for those exposed during gestati on was 1.8 [95% Confidence Interval (CI): 0.9-3.5]. Thus, our study failed to demonstrate a significant association between prenatal exposure to mater nal stress and risk of non-affective psychosis. The possible explanations f or this finding are discussed. (C) 1999 Elsevier Science B.V. All rights re served.