Demographers and sociologists have studied and asked for a theory of childlessness for more than two decades, however, this specific choice of zero fertility has not interested economists. Nowadays, facts show us that permanent childlessness can concern up to 30% of all women of a cohort. This paper gives an endogenous fertility model that looks in detail to the mechanisms leading to fluctuations in childlessness. Two mechanisms are considered. The first mechanism goes through the inter-generational evolution of preferences, that can be either exogenous or endogenous. I show that under some values of the parameters, oscillatory dynamics of childlessness may arise. The second mechanism goes through the female labor market; a more gender parity labor environment and an increase in the fixed cost of becoming parents could be an explanation for the dynamics of fertility and childlessness that we have observed in the United States since the early nineteenth century.