Famines, especially in what are now the high-income nations, decreased in frequency and severity. Food prices fell. Meanwhile, modern medicine, sanitation, and pharmaceutical production began to develop. All these factors helped reduce the death rate and accelerate population growth. By 1945, the population of the world was slightly less than 2.5 billion, meaning that global population grew by 0.6 percent per year between 1800 and 1945.