“In March 2007, Spain introduced a national policy granting most new fathers two weeks of fully paid paternity leave. The policy proved exceptionally popular, with 55% of men eligible in the first year opting to take the paid time. The amount of leave covered by the program was doubled in 2017 and expanded to five weeks in 2018, with additional increases expected between now and 2021.

Economists studying the effects of the original 2007 policy examined what happened to families that had children just before and just after the program began, and found differences in the outcomes. While the early cohort of men who were eligible for paternity leave were just as likely to stay in the workforce as the men who weren’t eligible, they remained more engaged with childcare after their return to work, and their partners were more likely to stay in the workforce as well. In that sense, the program seems to have done what policy makers would have hoped.

Unexpectedly, though, the researchers also found that families who were eligible for the paternity leave were less likely to have kids in the future. In a study published in the Journal of Public Economics(paywall), economists Lídia Farré of the University of Barcelona and Libertad González of University of Pompeu Fabra estimate that two years on, parents who had been eligible for the newly introduced program were 7% to 15% less likely to have another kid than parents who just missed the eligibility cutoff. While the difference dissipated further into the future, even after six years, parents who had been eligible for the leave were still less likely to have a child again.”