During the twentieth century, particularly in the second half, the world’s population increased rapidly, climbing from 1.7 billion at the beginning of the century2 to 2.5 billion in 1950 and reaching 6.06 billion in 2000. 3 The main contributors to the world’s rapid population growth during the second half of the twentieth century were the developing countries, including the Arab states. Whereas the Middle Eastern populations (including those of Turkey and Iran) numbered roughly 68 million in 1914, 4 they amounted to 407 million by 2000, 5 representing an increase of almost six-fold in less than one century. As in other developing regions worldwide, rapid population growth in the Arab countries during the second half of the twentieth century was the outcome of rising natural increase rates, which climbed from approximately 1.5–2 per cent in the 1930s and 1940s to a peak of 3 per cent in the early 1980s. Since then, the natural increase rates in virtually all of the Arab countries, with the exception of Yemen, have decreased considerably, due to a steady decline in fertility rates. By 1998, the average natural increase rate in the Middle East was 2.1 per cent (with a crude birth rate of 28 per 1000 and a crude death rate of 7 per 1000) and the average total fertility rate was 3.8 per cent. However, despite the substantial fertility reduction, the natural increase rate of the Middle East is still the highest worldwide, following sub-Saharan Africa. 6