Unrealized fertility in demography

BACKGROUND: Over the past few decades, demographic research on unrealized fertility – the experience of having fewer children than desired – has expanded rapidly, particularly in low-fertility settings. More recently, scholars have shown that unrealized fertility is also widespread in higher-fertility contexts, affecting individuals across diverse sociodemographic conditions. Yet the literature remains fragmented, spanning definitions and measurement approaches, and with limited synthesis across settings. OBJECTIVE: This article reflects on the current state of demographic research on unrealized fertility. Drawing on studies from both the Global North and Global South, we provide a narrative review of how unrealized fertility has been measured, its primary causes, and the persistent gaps in the field. RESULTS: We identify five dominant approaches to measuring unrealized fertility and review their strengths and limitations, as well as the data constraints that hinder cross-contextual comparisons. We then consider the principal causes of unrealized fertility and introduce a preliminary conceptual model for understanding its multilevel drivers. Finally, we highlight key gaps in the literature and propose substantive and methodological directions for future research. CONTRIBUTION: As unrealized fertility is increasingly the focus of public discourse and policy debates, this is a critical moment for demography to deepen and standardize research on the topic. Our review synthesizes the field to date and offers concrete recommendations for advancing demographic research on unrealized fertility.