Abstract
This paper investigates the causal effect of motherhood on women's occupational class trajectories-the Motherhood Class Penalty-using data from the 1970 British Cohort Study. We apply sequence optimal matching alongside other matching techniques to construct counterfactual class trajectories for mothers in the UK. Our results show that motherhood significantly increases downward mobility and limits access to professional occupations. Low professional women face an estimated 15% penalty, while high professional women experience a 5% penalty compared to their childless counterparts. We find that professional-class women are more likely to remain attached to the labour market after childbirth, whereas working-class mothers are at greater risk of permanently exiting the workforce. Among all groups, low professional women experience the most significant forgone upward mobility, highlighting how motherhood penalties vary across the class spectrum. These findings stress the substantial human capital loss associated with motherhood in the UK and suggest that occupational penalties are shaped by existing socio-economic hierarchies, potentially reinforcing broader patterns of inequality.