As in many other developed countries, Ireland has experienced a postponement of maternity. Whilst a number of authors have commented on this trend, suggesting greater female participation in the workforce results in delayed maternity, to date little research has tested this proposition. We develop a model to consider the main trends related to the phenomenon of maternity postponement, considering changes in first and later births separately. Using retrospective life history data developed from the 1994 Living In Ireland Survey we estimate a hazard model to empirically test the relationship between career planning and the timing of first and subsequent births. We incorporate a declining marginal return to experience and thereby provide a human capital/career planning explanation for maternity postponement. The results of our analysis demonstrate that career planning has an impact on the timing of maternity. The findings also establish an income effect that influences the timing of first births.