Prior to the 1921 census, India's population growth pattern was irregular, sometimes showing negative growth (as in the decade 1911-1921) due to high mortality rates from famines, epidemics (like the influenza pandemic of 1918-19), and poor health conditions offsetting high birth rates. However, after 1921, improvements in health and sanitation led to a consistent decline in the death rate, while the birth rate remained high. This resulted in a steady and accelerating population increase in subsequent decades. Thus, 1921 marked the transition from a fluctuating population growth phase to one of continuous and relatively rapid growth.