India's fertility rate is rapidly approaching the rates of China, Russia, and the US. In recent years Russia's rate has been slightly higher than China's. Between 1960 and 2016, all four of these countries have seen very significant increases in real GDP per capita. The level of GDP per capita in the US is highest. But the growth rate is higher for China and India. What are some reasons why GDP per capita has risen while fertility rates have fallen in those counties. Add emphasis on the differences of growth and fertility rates among the countries.