Global fertility rates currently stand at 2.5 children per woman. But according to the UN , half of the people on the planet may already be living in a country with replacement fertility rate. That means for every man and woman in the country there are two children living to childbearing age.The interactive below maps the changes in total fertility rates since 1950. Use the arrows to navigate backwards and forwards through the decades. Check the bubble chart to see how the UK compares to the world average, and to the countries with highest and lowest rates.