Milk flow and sucking rates during breast-feeding.

This study examined sucking patterns during breast-feeding in order to investigate the supposed 'nutritive' and 'non-nutritive' sucking dichotomy. The intervals between sucks were determined: they indicated that there is no bimodal distribution corresponding to 'nutritive' and 'non-nutritive' rates of sucking, but rather a complete gradation between the two. In a further experiment in which milk flow was assessed by test-weighing the baby at three-minute intervals during feeding, there was a linear relationship between milk flow and sucking rate: the higher the milk flow, the lower the sucking rate. These results were further substantiated by testing the sucking rate on an empty and full breast, and the sucking pattern of an infant with a non-lactating mother. The study shows that there is no dichotomy between two sucking rates, but rather a continuous variation in response to milk-flow rate.