Unfortunately, we cannot estimate this model because it requires at least two instrumental variables that were not available in our survey. Additionally, given the characteristics of the eph survey, it is not possible to identify patterns of delayed childbirth because there is no information about the age of the oldest child in the case of women with children aged over 14. The best approximation is to consider the same set of wage regressions but look at different female age cohorts.15 When this is done, the findings suggest that younger cohorts of mothers are likely to experience a higher wage penalty than older mothers.