The monthly distribution of live births was analyzed over a 51-year period, 1926-1976, for a rural Taiwan fishing community. Unlike previous studies of birth seasonality, monthly distributions of births did not deviate from what would be expected by chance. This new case is shown to be consistent with the suggestion, developed by Pasternak during a study of birth seasonality in two Taiwan farming communities, that for peasant cultivators the annual cycle of production exerts a more decisive influence on birth seasonality than time of marriage or attributes of temperature, rainfall, or workload. An hypothesis that links the productive cycle to conceptions through the intervening variable of diet is presented and successfully tested using several sets of data on monthly births. A direct effect of nutrition on human fertility, suggested by recent studies of reproductive performance under conditions of nutritional stress, may largely explain seasonality of conceptions and births in populations that experience significant seasonal variation in diet. © 1979 Plenum Publishing Corporation.
