The standard errors for the quantile regressions are computed using data analysis and statistical software (stata) and are based on 100 bootstrap replications. The reference category is a blue-collar single woman with less than complete secondary education who is a non-mother, public worker and is employed full-time at a small services firm. The control variables are the same as in table 2. Significant at 5%. *** An alternative approach is to consider penalties associated with the age of children or the timing of childbearing.