Low fertility is set to worsen economic problems in many developed countries, and maternity, paternity, and parental leave have emerged as key pro-natal policies. Gender inequity in the balance of domestic and formal work has been identified as a key driver of low fertility, and leave can potentially equalise this balance and thereby promote fertility. However, the literature contends that evidence for the effect of leave on fertility is mixed. We conduct the first systematic review on this topic. By applying a rigorous search protocol, we identify and review empirical studies that quantify the impact of leave policies on fertility. We focus on experimental or quasi-experimental studies that can identify causal effects. We identify 11 papers published between 2009 and 2019, evaluating 23 policy changes across Europe and North America from 1977 to 2009. Results are a mixture of positive, negative, and null impacts on fertility. To explain these apparent inconsistencies, we extend the conceptual framework of Lalive and Zweimüller (2009), which decomposes the total effect of leave on fertility into the “current-child” and “future-child” effects. We decompose these into effects on women at different birth orders, and specify types of study design to identify each effect. We classify the 23 studies in terms of the type of effect identified, revealing that all the negative or null studies identify the current-child effect, and all the positive studies identify the future-child or total effect. Since the future-child and total effects are more important for promoting aggregate fertility, our findings show that leave does in fact increase fertility when benefit increases are generous. Furthermore, our extensions to Lalive and Zweimüller’s conceptual framework provide a more sophisticated way of understanding and classifying the effects of pro-natal policies on fertility. Additionally, we propose ways to adapt the ROBINS-I tool for evaluating risk of bias in pro-natal policy studies.

低生育率将加剧许多发达国家的经济问题，产假、陪产假和育儿假已成为关键的生育政策。家庭和正式工作平衡中的性别不平等已被确定为低生育率的一个关键驱动因素，而休假可以潜在地平衡这种平衡，从而促进生育率。然而，文献认为休假对生育率影响的证据好坏参半。我们对这个主题进行了第一次系统评价。通过应用严格的搜索协议，我们确定并回顾了量化休假政策对生育率影响的实证研究。我们专注于可以识别因果效应的实验或准实验研究。我们确定了 2009 年至 2019 年间发表的 11 篇论文，评估 1977 年至 2009 年欧洲和北美的 23 项政策变化。结果是对生育率的正面、负面和无效影响的混合。为了解释这些明显的不一致，我们扩展了 Lalive 和 Zweimüller (2009) 的概念框架，将休假对生育的总体影响分解为“当前孩子”和“未来孩子”效应。我们将这些分解为对不同出生顺序的女性的影响，并指定研究设计类型以识别每种影响。我们根据确定的效应类型对 23 项研究进行分类，揭示所有负面或无效研究都确定了当前儿童效应，所有积极研究都确定了未来儿童或总效应。由于未来儿童效应和总体效应对于促进总生育率更为重要，我们的研究结果表明，当福利增加幅度很大时，休假确实会增加生育率。此外，我们对 Lalive 和 Zweimüller 概念框架的扩展提供了一种更复杂的方式来理解和分类生育政策对生育的影响。此外，我们提出了调整 ROBINS-I 工具以评估产前政策研究中的偏倚风险的方法。