ABSTRACT
The classical paradigm of the demographic transition features a decline in the rate of reproduction from the conditions of natural fertility at high levels to a regimen in which fertility is highly controlled and has declined to replacement or lower levels. In many of the developing countries that have entered this transitional stage, increases in age at marriage have played an important role. But the principal mechanism driving this transition is birth control, mainly in the form of contraception, though abortion has made significant impacts at different times and in different places.
