The British Journal of Psychiatry
Season of birth of siblings of schizophrenic patients.
A E Pulver, K Y Liang, P S Wolyniec, J McGrath, B A Melton, L Adler, B Childs


The hypothesis that mothers of winter-spring-born schizophrenics have an unusual pattern of conception which results in an excess of winter-spring births was tested by studying the distribution of birth-dates of 401 siblings of 120 winter-spring-born schizophrenics and 157 siblings of 59 winter-spring-born controls. All analyses were gender-specific. The results suggest there is no association between the probability of a winter-spring date of birth and being a sibling of a winter-spring-born schizophrenic or control.