In this paper we compare cohorts of mothers who had their first children between 1970 and 1999, in terms of their probability of beginning work shortly after childbearing. Using the 2001 General Social Survey, Cycle 15 on Family History, we investigate the effects of women's socioeconomic characteristics on labor force withdrawal. Our discussion focuses on the analysis of the transition as a type of life course analysis. We underline the differentiation of the transition by cohorts, educational attainment, income, et cetera. We show that since the mid-1980s, mothers with low educational attainment are dramatically excluded from the labor market within the two years following the birth of their first child.