This document aims to provide evidence on the association between economic conditions and household fertiliTY decisions related to birth spacing by using a Cox proportional hazards model. The contribution of the paper is twofold: first, it adds to the scarce existing literature on this topic for Latin America by offering evidence for Colombia; second, local heterogeneiTY in economic performance is considered by using regional economic growth as a shock potentially modifying household decisions. We find that better economic performance is associated with reductions in birth spacing. Thus, it seems that demand for children might be procyclical, an income effect predominating; however, when good conditions persist, demand for children decreases, suggesting the dominance of a substitution effect. An alternative interpretation is simply that economic growth increases the probabiliTY of having children, automatically reducing the risk after the boom.