Schizophrenia After Prenatal Famine-Reply

In Reply We thank Dr van Os for his thoughtful comments and careful reading of our work. In addition, his letter provides us with a welcome opportunity to demonstrate that social class confounding cannot account for our result from the Dutch famine study. 1 First, if there were confounding due to social class of origin, it would most likely have diminished the association between prenatal exposure to famine and the risk of hospitalization for schizophrenia. As Dr van Os rightly indicates, the lower class was underrepresented in the exposed cohorts. Most studies suggest that individuals in the lower class are at an increased risk of hospitalization for schizophrenia; therefore, the effect would be to reduce the observed risk in the exposed cohort and to reduce the relative risk of hospitalization for schizophrenia. The result of the Dutch study 2 to which Dr van Os refers was atypical. That study included only a