Do Shorter School Days Reduce Fertility?

Muñiz-Fernández (2026) examines whether shortening the school day, and thereby reducing school-based childcare, affects fertility. He analyzes annual data from 50 Spanish provinces from 1981 to 2016, including total fertility rates and women’s age at first birth. Using a synthetic difference-in-differences approach, he finds that shifting from full-day to morning-only school reduced fertility by 0.12 children per woman, about a 9% decline, and delayed first births by roughly four months. Effects were much larger where shorter schedules were mandatory: fertility fell by 0.38 children per woman and first births were delayed by about seven months.

Why This Article Was Selected for The Policy Scientist

School schedules are an important but often overlooked part of family policy because they shape childcare availability, parents’ ability to work, and the costs associated with raising children. These issues are especially timely as many developed countries confront declining fertility and delayed childbearing. Muñiz-Fernández makes an important contribution by showing that policies not designed as family benefits can nonetheless influence fertility decisions. The long provincial panel provides strong data, while the synthetic difference-in-differences design offers substantially stronger causal evidence than conventional multivariate regression. Published in the Journal of Policy Analysis and Management, a leading public-policy journal, the study is particularly relevant to jurisdictions considering changes in school schedules, although Spain’s institutional and labor-market context limits direct generalization.

Full Citation and Link to Article

Muñiz-Fernández, Á. (2026). The fertility effects of reducing implicit childcare subsidies: The case of school schedules. Journal of Policy Analysis and Management, 45(4), e70124. https://onlinelibrary.wiley.com/doi/full/10.1002/pam.70124

Central Research Question

The study asks whether reducing an implicit form of publicly provided childcare affects fertility decisions. In Spain, many elementary schools shifted from traditional schedules that included morning and afternoon classes to “intensive” schedules ending around 2:00 p.m. rather than 4:00 or 5:00 p.m. Although the reform concerned school organization rather than family policy, the longer school day had effectively provided several hours of childcare while many parents were working. The central question is therefore whether eliminating this implicit childcare subsidy caused families to have fewer children, postpone childbearing, or both. The analysis also investigates whether effects differ according to how the reform was implemented, birth order, maternal age, and local female labor-force participation.

Previous Literature

The study connects research on fertility with a growing literature examining how public institutions affect the costs of raising children. Lalive and Zweimüller (2009), Raute (2019), and Bergsvik et al. (2021) provide evidence that explicit family policies, including parental leave and childcare subsidies, can influence fertility. Bratti et al. (2018), Eibich and Siedler (2020), and Ilciukas (2023) broaden this perspective by showing that policies not explicitly designed as childcare programs can indirectly alter families’ access to care. More recent work by Dow (2026) finds that childcare prices affect fertility in the United States.

A particularly relevant literature examines school schedules. Cabrera-Hernández and Márquez-Padilla (2023) find that extending the school day in Mexico reduced fertility, although through a mechanism different from the one emphasized in Spain. Berthelon and Kruger (2011) find that full-day schooling in Chile reduced adolescent motherhood. Padilla-Romo and Cabrera-Hernández (2019) and Berthelon et al. (2023) show that longer school schedules can increase female labor-force participation, while Berthelon et al. (2024) document improvements in job quality. Padilla-Romo et al. (2025) further demonstrate that extended school schedules can affect household behavior. The study therefore places fertility within a broader framework in which school schedules influence families not merely through education but also by changing time constraints and childcare costs.

Data

The analysis uses annual administrative data for Spain’s 50 provinces covering 1981 through 2016. The principal outcomes come from Spain’s National Statistical Institute. The first is the total fertility rate, an age-standardized measure representing the number of children a woman would have if current age-specific fertility rates persisted throughout her reproductive years. The second is the mean maternal age at first birth, which captures the timing of entry into motherhood. Fertility rates are also separated by birth order, allowing the analysis to distinguish first births from second, third, and fourth-or-higher births.

The principal explanatory variation comes from the staggered transition from full-day to morning-only school schedules. Implementation differed substantially across regions. Some regional governments required public schools to adopt the shorter schedule, while others permitted individual schools to decide whether to adopt it. Some regions retained traditional full-day schooling.

The analysis incorporates provincial socioeconomic characteristics that could independently influence fertility, including GDP per capita, male and female unemployment rates, educational attainment, and the age distribution of women. These controls are lagged by one year. Additional data are used to examine possible mechanisms, including public-school enrollment, female labor-force participation, and migration.

Methods

The empirical strategy exploits differences across provinces and over time in the adoption of shorter school schedules. A conventional difference-in-differences model would compare changes in fertility in provinces exposed to the reform with changes in provinces that retained full-day schooling. However, the author finds evidence that treated and untreated provinces did not consistently follow parallel trends before treatment, weakening a central assumption underlying a standard difference-in-differences design.

The principal identification strategy is therefore synthetic difference-in-differences (SDID), following Arkhangelsky et al. (2021). SDID combines features of difference-in-differences and synthetic-control methods. It reweights untreated provinces and pre-treatment periods to construct counterfactual outcomes that more closely reproduce the pre-reform trajectories of treated provinces. Province and year fixed effects are included, and statistical uncertainty is estimated using 500 clustered bootstrap replications.

Interpretation differs between mandatory and voluntary reforms. Mandatory adoption provides an average treatment effect on treated provinces because all relevant public schools were required to change schedules. In voluntary regions, the estimates are better interpreted as intent-to-treat effects because individual schools could choose whether to adopt the shorter day.

The study conducts extensive robustness analyses. These include alternative difference-in-differences estimators, placebo tests using marriage rates, tests excluding regions that introduced other family policies, and analyses of migration. The results are generally consistent across these alternative specifications.

Findings/Size Effects

The central finding is that reducing school-based childcare decreased fertility and delayed motherhood. Across treated provinces, moving from full-day to morning-only schooling reduced the total fertility rate by approximately 0.12 children per woman. Relative to a pre-reform fertility rate of roughly 1.40, this represents about a 9 percent decline. The reform simultaneously increased maternal age at first birth by approximately 0.31 years, or about four months.

Effects were considerably larger where adoption was mandatory. In those provinces, fertility declined by approximately 0.38 children per woman, while maternal age at first birth increased by about 0.59 years, or seven months. In regions where schools could voluntarily adopt shorter schedules, fertility declined by approximately 0.10 children per woman and first births were delayed by roughly three months.

The decline primarily reflects fewer additional children rather than a large reduction in entry into parenthood. The reform produced no aggregate reduction in first births but reduced second births by approximately 0.03 children per woman, third births by another 0.03, and fourth-or-higher births by approximately 0.05. Thus, much of the overall fertility decline resulted from families becoming less likely to progress to higher-order births.

Labor-market conditions were especially important for the timing of motherhood. In provinces with relatively low female labor-force participation before the reform, maternal age at first birth increased by roughly eight months, compared with approximately two months in provinces with higher female labor-force participation. Differences in the overall fertility decline across these two groups, however, were not statistically significant.

The study also finds evidence of behavioral adaptation. Public-school enrollment declined by approximately 1.9 percentage points following the reform and by more in areas with voluntary adoption. This pattern is consistent with some families moving children toward alternative schooling arrangements that provided longer hours. Additional analyses find no significant changes in marriage or female migration that could readily account for the fertility results.

Conclusion

The results indicate that school schedules can function as an important form of implicit childcare policy. When Spanish schools eliminated afternoon instruction, families lost two to three hours of institutional childcare during a portion of the day when many parents remained at work. The resulting increase in the effective cost of raising children affected both when families had children and how many children they ultimately had.

The findings also distinguish between postponing parenthood and reducing fertility. Shorter school days delayed first births, particularly where women had weaker pre-reform attachment to the labor market, but the reduction in overall fertility was concentrated primarily among second and higher-order births. The evidence therefore suggests two related responses to reduced childcare availability: couples may postpone entering parenthood while also becoming less likely to have additional children.

More broadly, the study demonstrates that demographic behavior can respond to policies that are not formally classified as family policy. Decisions about school hours are ordinarily evaluated in terms of educational outcomes, administrative costs, or student performance. Because schools also provide childcare during working hours, however, changes in their schedules can alter household time constraints and the effective cost of childbearing. The study consequently expands the analysis of fertility policy beyond explicit benefits such as parental leave, childcare subsidies, and birth allowances to include the broader institutional arrangements through which governments indirectly affect the costs families face.