Geophysical Variables and Behavior: XVII. Mental Retardation and Seasonality of Birth: A Racial Analysis

The records of 1174 mentally retarded people were analyzed with regard to patterns of seasonality of birth. A population model was derived from birth records of the general population born during the same time period as the mentally retarded people. Log-linear analyses uncovered no significant differences between the seasons of birth for the mentally retarded and those in the general population. There were also no significant relationships when the data were analyzed by race and sex. Given the sample size and the sophistication of the analytic model, these results have important implications for an unresolved literature.