Having children can result in a large dent in the mother’s later earnings but fathers’ incomes are unaffected by childbirth, new research by the government’s macro-economic think-tank CPB shows.

The CPB’s researchers analysed extensive administrative data to assess the effects of a first child on earnings. They found that seven years after the birth, mothers are earning 46% less than would have been expected, given their pre-child career.

While the availability of childcare does reduce the impact of having a child on women’s earnings, the immediate impact of expanding access to childcare has been minor, the researchers say.

‘This, however, does not rule out an important role for childcare policies in the long run, as they may have an effect on other determinants of the child penalty – such as gender norms.’

By comparing different groups, the researchers were able to show that the drop in income for mothers – what they call the child penalty – in female-female couples is almost a third smaller than in female-male couples.

It was also less in Surinamese and Antillean communities, where women are used to work longer hours.

In addition, mothers in religious communities are also likely to earn much less after giving birth, again indicating traditional roles are behind the impact on income.

Part-time

Some 74% of Dutch women do not work the standard 40-hour week – on average they work just 28 hours. And research last year by the socio-cultural think-tank SCP showed that women are underrepresented in managerial roles because they are more likely to work part time.

Only when people work at least 28 hours a week, are they likely to move into middle management jobs, with higher earning potential, the SCP researchers said.

Several political parties have called for childcare to be made cheaper or even free to encourage more mothers to work.

Last week the OECD said the Netherlands needs to do more to encourage more women to work full time. This, the agency said, could involve changing school opening hours – the Dutch school day ends early compared with many other countries – as well making childcare cheaper.