In recent decades, shifts in childbearing patterns have emerged as a central theme in sociological and demographic studies. The persistent fertility decline represents not merely a demographic crisis, but a manifestation of profound structural transformations requiring evidence-based interventions and policymaking. Therefore, this study aimed to develop an Interpretive Structural Model (ISM) of factors contributing to the decline in childbearing desires through a sociological perspective in the metropolis of Mashhad.This applied research adopted a qualitative methodology. Initially, 16 key factors were identified through a literature review coupled with semi-structured interviews with 12 purposively sampled academic experts. Subsequently, Interpretive Structural Modeling (ISM) and Matrice d’Impacts Croisés Multiplication Appliquée à un Classement (MICMAC) analysis were utilized to determine causal interrelationships and establish hierarchical levels among the identified factors.The ISM analysis revealed that the factors influencing the decline in childbearing desires are structured across nine hierarchical levels. The root-cause drivers—characterized by maximum driving power—include “women’s increased education and employment,” “economic pressures and livelihood concerns,” and “job insecurity and income instability.” These foundational drivers operate through intermediate variables such as “the proliferation of individualism,” “attitudinal shifts toward family and childbearing,” and “future uncertainty,” ultimately culminating in outcome factors including “biological barriers and advanced reproductive age” alongside “decreased willingness to assume parental roles.” Furthermore, the MICMAC analysis confirmed that “women’s increased education and employment” exhibits the highest driving power and lowest dependence among the 16 factors.The findings indicate that fertility decline in Mashhad is a multifaceted phenomenon. Given that economic constraints and female employment serve as fundamental structural drivers, unidimensional policies prove ineffective. Mitigating this challenge necessitates restructuring livelihood supports, enhancing job security, and fostering a genuine work-family balance, thereby modulating the root drivers to revitalize childbearing inclinations at the terminal levels of the system.