Journal article: In this article, we study the joint dynamics of the demography and the economy. We explore how economic conditions affect fertility choices, and in return how the population growth rate affects both financial and labor markets. Our main contribution is to consider a realistic demographic setup that allows characterizing the age at which individuals decide to give birth to their children. In such a framework, we aim at studying the existence of an equilibrium. We notably prove there exists a monetary steady state if the average age of consumers is greater than the average age of producers.