The expansion of the pubic symphysis during pregnancy in some rodent species depends on the growth of the interpubic ligament, primarily through the biosynthesis of extracellular matrix. Although there is a significant metabolism of elastin in the female reproductive tract during pregnancy, little is known of the architectural and ultrastructural aspects of the elastic system fibers in the mouse pubic symphysis. In this study, the main characteristics of the elastic system of the mouse pubic symphysis during pregnancy, partum and post-partum were determined by light and electron microscopy. A distinct arrangement of microfibrils, elastin deposition and development of the thin elastic fiber network was observed during pregnancy and after delivery. The elastic system fibers of the extracellular matrix formed a supporting framework that uniformly distributed stress in order to provide adequate interpubic resilience during delivery. These changes support a role for elastic system fibers in symphyseal maturation and reconstruction during pregnancy and after delivery.