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The monthly distributions of 6846 births during the period 1840-1899 inclusive in two neighbouring rural districts of Tasmania, Australia, were investigated for seasonality. Both districts displayed seasonal birth patterns, modeled through time series analysis and Edwards’ test for seasonality, but the cycle was more pro­nounced in the district with the considerably larger population. A 24-month effect was identified and probably explained by birth interval. There was a birth max­imum in September and a minimum in January. No changes in this cycle, over time, were evident. Social class analysis demonstrated that only the farmers had a significant seasonal cycle and that this group essentially accounted for the seasonality in the larger community. The autumn conception minimum could not be explained through climatic factors or seasonality of marriage, but was most likely a result of farmers and some of their employees grazing sheep on higher altitude pastures at this time.