John Caldwell developed the theory of intergenerational wealth flows at the micro-family level, which suggests that changes in family economic relations, particularly changes in the direction of intergenerational wealth flows within families, have led to fertility transition. It is undoubtedly original, but there are problems with its application and explanation. Based on the empirical facts described by the theory, an attempt is made to operationalize its concepts and core propositions, and to illustrate them empirically with the indicators and data provided by the National Transfer Accounts (NTA). It is found that introducing the direction of intergenerational wealth flows at the public level leads to more combinations of the direction of intergenerational wealth flows at different levels. Along with population ageing, changes in the direction of public-level intergenerational wealth flows can lead to a bottom-up shift in the direction of the aggregated flow. The shift is influenced by the demographic factors and the average age-specific transfers.