Over the long term the general fertility rate (the number of births per thousand women ages 15 _ 44) has moved sharply downward. Between 1800 and 1910 the rate fell by more than half, and between 1910 and 1980 it again fell by half. Most economists believe that this long-term downward trend, which has its counterpart in all economically developed countries, can be explained by three types of changes: a decrease in the benefits to parents from having children, an increase in the costs of having children, and a decrease in the costs of avoiding having children – that is, the costs of birth control.
The benefits of children are many and varied. For most parents children are a source of pride and delight, a link with the future, an object and a source of love and affection. In agricultural societies children are often valued for their contribution to production; in that sense the demand for them is analogous to the demand for farm machinery,
Moreover, in societies that lack banks, insurance companies, and other financial institutions, investment in children is a principal method of providing for the future.