The World Fertility Rate
The World's fertility rate was very high in 1950-60. The total fertility rate was around 6.But, the world's population was not too high because of the high mortality rate.This was because of the lack medicines even for the normal diseases and vaccinations. People used to have big families but the survival rate of the babies was so low.
In the modern age, the situation is totally reversed. All the medicines and vaccinations are easily available. But the world replacement level of fertility is going down.Replacement fertility is the total fertility rate at which women give birth to enough babies to sustain population levels. The replacement level of TFR would be very close to 2.0. The replacement fertility rate is indeed only slightly above 2.0 births per woman for most developed countries (2.075 in the UK, for example), but ranges from 2.5 to 3.3 in developing countries because of higher mortality rates, especially child mortality.
If we go with the fertility rate by country, The total fertility rate in the US after World War II peaked at about 3.8 children per woman in the late 1950s and by 1999 was at 2 children. The fertility rate of the total US population was just below the replacement level of about 1.9 children per woman in 1979.However, the fertility of the population of the United States is below replacement among those native born, and above replacement among immigrant families, most of whom come to the U.S. from countries with higher fertility than that of the U.S. As of the beginning of 2016, there are 59.8 births per 1,000 women aged 15–44; this is the lowest number since records have been kept since 1909.
The average total fertility rate in the European Union (EU-28) is calculated at 1.58 children per woman in 2015. France has the highest TFR at 1.96, followed by Ireland (1.92).