• cohort;
  • gender;
  • labor market;
  • motherhood;
  • wage penalty;
  • work-family

Several recent studies have shown a negative association between motherhood and wages. However, an analysis of change over time in the motherhood penalty has not been conducted. Using two cohorts of young women drawn from the 1975–1985 National Longitudinal Survey of Young Women and the 1986–1998 National Longitudinal Survey of Youth, we explicitly test the relationship between motherhood and wages across two cohorts and examine whether that relationship has changed. Even after controlling for unobserved heterogeneity and human capital variables, each additional child is associated with a negative effect on women's wages. Moreover, our findings suggest that the penalty has not diminished over time.