PAYROLL clerks across Britain are busier than usual. By April next year large employers must publish data on the gap in pay between their male and female workers. Many have already complied. In America, by contrast, President Donald Trump recently halted a similar rule that would have taken effect next year. Such requirements are meant to energise efforts towards equal pay for men and women. The data suggest that a new approach is needed. In the OECD, a group of rich and middle-income countries, median wages for women working full time are 85% of those for men. Why do women still earn so much less?

Contrary to popular belief, it is not because employers pay women less than men for doing the same jobs. According to data from 25 countries, gathered by Korn Ferry, a consultancy, women earn 98% of the wages of men who are in the same roles at the same employers. Women, however, outnumber men in lower-tier jobs, such as secretarial and administrative roles, whereas men predominate in senior positions. And women cluster in occupations and industries that pay lower salaries overall. Primary-school teachers in the OECD, for example, earn nearly 20% less than the average for university graduates. In the European Union nearly 70% of working women are in occupations where at least 60% of employees are female. In America, the four jobs done by the biggest numbers of women—teacher, nurse, secretary and health aide—are all at least 80% female.

The main reason why women are less likely than men to reach higher-level positions is that they are their children’s primary carers. In eight countries polled by The Economist and YouGov earlier this year, 44-75% of women with children living at home said they had scaled back at work after becoming mothers—by working fewer hours or by switching to a less demanding job, such as one requiring less travel or overtime. Only 13-37% of fathers said they had done so, and more than half of those men said their partner had also scaled back. This pattern means that men get a better shot at a pay rise or a promotion than their female colleagues, and are less likely to be in jobs for which they are overqualified. A recent study estimated that in America women’s future wages fall, on average, by 4% per child, and by 10% per child in the case of the highest-earning, most skilled white women. In Britain, a mother’s wages fall by 2% for each year she is out of the workforce, and by twice as much if she has good school-leaving qualifications.

Women’s lower salaries mean that they often fall into poverty when they divorce or are widowed. Lack of financial independence prevents some from leaving abusive partners. Policies and workplace norms that make it easier for men to split parental duties equally with their partners can tip the scale. Parents, for their part, need to instil in their children the idea that they can be anything—and not only if they are girls. Gender equality will remain elusive until boys are as excited as girls about becoming teachers, nurses and full-time parents.