The consequence was a widening of the gap between women in poor families and those in middle- to high-income ones. For their part, women in lower-income sectors might stay at home and care for their children, participate in community arrangements to secure food and services for them, or join the labour market and secure child care (Faur, 2011). However, it also seems to be important to consider the evolution of female labour force participation, fertility patterns and the increasing probability that a woman will have her first baby at an older age. The ideal estimation would be a double selection model covering the probability of being in the labour force and of being a mother and taking account of sample selection as well as the endogeneity of the choice to become a mother.