In this paper we anaIyze the effect of female labor force participation on fertility decisions. We focus on two issues that emerge when estimating such effect: (i) the endogeneity between fertility and participation; and (ii) the period in which participation is measured with respect to fertility. We account for the first problem by using an empirical model based on the assumption that women decide on labor force participation and childbearing in response to incentives provided by prices and incomes. The second issue is addressed exploiting the panel structure of our data (matched EPA files). which allow us to measure women labor force participation at several points in the time preceding a birth. Our results show that it is important to account for the endogeneity between participation and fertility and that women's attitude toward the labour market changes along the pregnancy