Comparative research on the effects of long periods of leave, however, has been taking a variety of strategies – not all of them optimal. So, based on a literature overview and our own empirical research, we formulated four recommendations for studying the impact of long childcare leave on women’s employment:

• The relationship between duration of leave and employment of women is curvilinear: whereas long leave may reduce women’s employment, we should not overlook that short period can be beneficial (and vice versa).
• Childcare leave is expected to affect only mothers, not women without children.
• Testing the long-leave hypothesis requires the use of country-comparative data in which countries are observed repeatedly over time. Among other benefits, this reduces the sensitivity of the analyses to influential cases.
• The long-leave hypothesis is best tested against person-level data.

Nieuwenhuis, R., Need, A., & Van Der Kolk, H. (2017). Is there such a thing as too long childcare leave? International Journal of Sociology and Social Policy, 37(1/2), 2–15. http://doi.org/10.1108/IJSSP-07-2015-0074