Variety expansion and fertility rates

To investigate how fertility rates interrelate with the modern economy, we construct a simple model in which variety expansion of consumption goods reduces fertility rates. In our model, variety expansion reduces the relative price of a composite of differentiated goods compared to child-rearing costs. Thus, parents raise the expenditure share for differentiated goods and lower the number of children. We show that this model can be applied to a growth model in which economic growth progresses with variety expansion of consumption goods and fertility rates decrease with economic growth. Thus, we show a new mechanism for fertility decline, and this mechanism can be applied to a growth model.