Modelling the temporal trajectories of human milk components.

Abstract

This paper demonstrates how available data can be explored and utilized to conclude generic patterns in the temporal changes in Human Milk (HM) composition. The temporal trajectories of selected human milk components (HMC-s) were described, in the first four months postpartum, by a primary model consisting of two phases: a short linear phase in the colostrum, triggered by the parturition; and a longer second phase, where the concentration of the component converges to a steady state. The model was fitted to data available in a recently published database of temporal HMC trajectories both at the levels of individual molecules (such as specific fatty acid, oligosaccharide, and mineral molecules) and molecule-groups (such as total protein, total fat). The properties of the trajectories suggest that experimental designs should follow non-equidistant sampling times, with increasingly longer time intervals after the first week postpartum. A selected parameter, the final stationary level, of the primary model was then studied as a function of geographical location (secondary modelling). We found that the total variation of the concentration of specific HMC-s is dominantly due to the inherent biological differences between individual mothers and to less extent to the geographical location.