Why was it that in the second half of the twentieth century the rate of population growth in Europe slowed down, while in America and other Third World areas it accelerated?

The factors responsible for the population growth in America and other third world countries are as follows:

• The improvement in medical facilities and hygiene techniques resulted in falling of infant and child mortality rate. Deadly diseases like small pox, malaria and typhoid were brought under control
• The people did not paid attention to population control either due to their incapability to buy contraceptives or ignorance. The Roman Catholic Church said that using contraceptives were against their religion so the population in countries like Central and South America doubled in thirty years.
• The tradition in third world countries to have as many as children to combat high infant mortality rate.

But in case of America, immigration was the major contributing factor for the rise in population. And the population growth slowed down in Europe mainly because of more people started using contraceptives unlike the third world countries.