The population in both the old and new federal states began to decline in the 1970s because the birthratewas falling. Despite an increase in the number of births in 1996, Germany has one of the lowest birthrates in the world: 10.5 births per 1,000 inhabitants per year (in the western part of the country). The population increase after the Second World War was mainly due to immigration. Some 13 million refugees and expellees entered the present German territory from the former German eastern provinces and Eastern Europe.

There was a continuous strong flow of people who fled from eastern to western Germany until the Berlin Wall was erected by the regime in the former German Democratic Republic (GDR) in 1961, which hermetically sealed the border. Beginning in the early 1960s, large numbers of foreign workers came to the Federal Republic of old whose expanding economy needed additional labor which was not available at home.