In the present more developed regions combined, the birth rate may have averaged 38 per 1,000 during 1850-1900 and 26 per 1,000 during 1900-1950, the average having fallen progressively as one region after another underwent this process of change. Post-war 'baby booms' led to an average birth rate of 23 per 1,000 in 1950-1960, subsiding to 19 per 1,000 in 1960-1970 and 15 per 1,000 in the last decade. Yet during all those decades, the average birth rate in the less developed regions combined is estimated at 40 or 41 per 1,000; and only in recent years, has this dropped to a still high 33 per 1,000. It is assumed that the annual average birth rate of the more developed regions will continue to fluctuate around 15 per 1,000 to the end of the century, whereas, during the same period, the average birth rate of the less developed regions may decrease even more decisively.
While the more developed regions tend towards greater uniformity in the level of crude birth rates, a wide range of conditions now seems to exist in the less developed regions. Among 22 countries of these regions, the crude birth rate around 1970 was reported as less than 30 in 7 countries, 30-40 in 6 countries, 40-50 in 6 countries, and above 50 in 3 countries. More recent statistics indicate Africa, as a continent, having 46 per 1,000 as a birth rate; Latin America having 31, and Asia, 30. The wide ranges on each continent continue, however. If China is excluded from the figures for less-developed countries, then the average is 37 per 1,000.