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The researchers featured in this article suggest that a higher incidence of schizophrenia may be due to summer-related infections “or other seasonal factors.” June and July births would have been in early gestation during late fall and winter, when there is increased incidence of depression among adults. Might it be reasonable to suggest that “other seasonal factors” might include some hormonal influences on the developing fetus?

Gene Addor
Steele, Ala.

Fetuses are most vulnerable in the second or third month of gestation. So, it seems much more likely that causative infections occurred the previous winter.

Sharon Rudahl
Los Angeles, Calif.