Abstract: This paper provides a unified growth theory, i.e. a model that explains the very long-run economic and demographic development path of industrialized economies, stretching from the pre-industrial era to present-day and beyond. Making strict use of Malthus (1798) so-called preventive check hypothesis - that fertility rates vary inversely with the price of provisions - the current study offers a new and straightforward explanation for the demographic transition and the break with the Malthusian era. The current framework lends support to existing unified growth theories and is well in tune with historical evidence about structural transformation.