<p>Fertility transitions have transformed both the number of births women have and the timing of those births across the reproductive lifespan. While indicators such as the total fertility rate and mean age at childbearing summarize fertility levels and central timing, they provide limited insight into how widely fertility is distributed across ages. This paper introduces the <i>childbearing span</i>, a simple percentile-based indicator measuring the number of years between the ages at which 10% and 90% of total fertility are reached. Using a global dataset for all countries and areas of the world from 1950 to 2025, the study presents the first global assessment of long-term trends in the concentration of fertility across reproductive ages. Findings reveal a consistent global compression of fertility over the past seven decades: the global average childbearing span declined from 18.9 years in 1950 to 16.8 years in 2025. This narrowing reflects both the postponement of childbearing and the convergence in fertility completion as high-order births become less common. Regional patterns vary considerably, with Eastern and South-Eastern Asia showing the strongest compression and sub-Saharan Africa maintaining wider fertility windows. The childbearing span offers a visually intuitive and globally comparable tool that complements existing indicators and enhances comparative analyses of fertility timing and distribution.</p>