We have to talk about the gender wage gap in Ireland. It’s the highest in the world. But there’s a catch. It’s not men earning more than women. It’s women — those without children, at least — earning more than men.

Irish women without kids earn 17 percent more than the typical male worker, according to new research from the OECD. Along with Australia, Luxembourg, and the Netherlands, it is one of four rich countries where women without children report higher wages than men. The graph below shows that gender pay gap. In Germany, the U.S., Korea, and Japan, by comparison, childless women average between 3% and 24% lower wages than men.

Once kids enter the picture, the picture changes.

The second graph here is the same as the first, but with red bars showing the gender gap that emerges when you compare female workers with children (many of whom move to part-time jobs) to all men. In Australia, women without children out-earn men more than any other country except Ireland; but after children, the wage gap plunges to U.S.-levels.

That leads us to the final graph: The cost of kids. I wanted to calculate and show how far women’s earnings fall behind men’s after they have children in each of these countries. This graph has the answer. In the Netherlands, women work almost 2 hours more per day than men, and female employment has climbed to over 70% if you factor in part-time workers, the cost of having children is about 7 percentage points compared to male earnings. In Korea, where more married women are expected to leave their jobs and female participation rates haven’t much budged for 20 years, according to OECD, female earnings plummet compared to men after kids.